Math Riddles With Answers- Part 2

Math Riddles With Answers
Math Riddles With Answers

Math Riddles With Answers

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Math riddles

There are 4 borthers 3 of them want to buy a television which is 30 pounds. Each of them pay 10 pound each they give the money to the fourth brother and asked him to go into town and buy the television. When he got there the man said there was 5 pounds off so the fourth brother took the 5 pound and television and left. He decided to make some money out of this so he took 2 pounds and give the other 3 pounds to his brothers. So the 3 brothers only payed 9 pounds each. 3 times 9 is 27 were is the last pound?
Click to Flip
Add 3 on to 25 = 28 then add 2

Math riddles

A girl is twice as old as her brother and half as old as her father. In 50 years, her brother will be half as old as his father. How old is the daughter now?
Click to Flip
50 years old.

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Math riddles

What is the value of 1/2 of 2/3 of 3/4 of 4/5 of 5/6 of 6/7 of 7/8 of 8/9 of 9/10 of 1,000?
Click to Flip
One hundred - work backwards and you will understand.

Math riddles

Three pirates, One Eye, Long John, and Peg Leg, were gambling with pieces of gold. All the winnings were piled up on the table. �One Eye said, 'I have won 1/2' and took a large handful or two. Long John said, 'I have won 1/3' and took a handful. Peg Leg said, ' I have won 1/6' and took a small handful. �One Eye said, ' I have taken too much' and returned a half. Long John said, 'I have taken too much' and returned a third. Peg Leg said, 'I have taken too much and returned a sixth. �The money on the table was then shared out equally and they had 42 pieces each. �One Eye said, 'I have now 1/2 of the total originally.' Long John said, ' I now have 1/3 of the originally.' �Peg Leg said, 'I have now 1/6 of the originally.'
How much was on the table originally?
Click to Flip
282 Pieces.

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Math riddles

A rubber ball is tossed off the top of a 90 foot building. Every time it bounces, it goes back up half way. How many bounces will the ball take before it stops?
Click to Flip
The answer is infinite, in a gravity free world. But of course gravity will eventually stop it.

Math riddles

As I traveled up and down our great glorious country, I found myself in a place where the tempature goes up sharply in the day and down at night. This had an effect on my watch, I noticed it was 1/2 a minute faster at nightfall, but at dawn it had lost 1/3 minute, making it only 1/6 minute fast.
One morning- May 1- my watch showed the right time. By what date was it 5 minutes faster?
Click to Flip
In 24 hours the watch gained 1/2-1/3= 1/6 minute. It would seem it would be 5 minutes fast in 5 X 6= 30 days; that is,the morning of May 31. But already on the morning of May 28 the was 27/6= 4 1/2 minutes fast. At the close of the day the watch gained 1/2 minute more, so it was 5 minutes fast on may 28.

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Math riddles

Express 100 with 5 1s. Express 100 three ways with five 5s. You can use brackets, parentheses and these signs +,-,X, /
Click to Flip
111-11=100
(5 x 5 x 5)-(5 x 5)=100; (5+5+5+5)x 5=100;(5 x 5)(5-(5/5)=100.

Math riddles

A boy presses a side of a blue pencil to a side of a yellow pencil, holding both pencils vertically. One inch of the pressed side of the blue pencil, measuring from its lower end, is smeared with paint. The yellow pencil is held steady while the boy slides the blue pencil down 1 inch, continueing to press it against the yellow one. He returns the blue pencil to its former position, then again it slides down 1 inch. He continues until he has lowered the blue pencil 5 times and raised it 5 times- 10 moves in all.
Supposed that during this time the paint neither dries nor diminishes in quantity. How many inches of each pencil will be sneared with paint after the tenth move?
Click to Flip
At the start, 1inch of the yellow pencil gets smeared with wet paint. As the blue pencil is moved downward, a second inch of the blue pencils smears a second inch of the yellow pencil.
Each pair of down and up movesof the blue pencil smears 1 more inch of each pencil. 5 pairs of moves will smear 5 inches. This together with the initial inch, makes 6 inches for each pencil.

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Math riddles

A watchmaker was telephoned urgently to make a house call to replace the broken hands on a clock. He was sik so he sent his apprentice.
The apprentice was thorough. When he finished inspecting the clock it was dark. Assuming his work was done, he attached the new hands and set the clock by his pocket watch. It was sic o'clock, so he set the big hand at the 12 and the little hand at the 6.
The apprectice returned, but soon the telephone rang. He picked up to his angry client:
"You didn't do the job right. The clock shows the wrong time."
Surprised he hurried back. He found the clock showing not much past eight. He handed is watch to the client and showed her that her clock was not even one second late. The client had to agree.
Early the nect morning, the client telephoned to say the clock has apparently gone berserk, hands were moving around the clock at will. The apprentice again rushed over, the clock showed a little past seven. After checking his watch he yelled:
"You are making fun of me! Your clock shows the right time!"
Have you figured out whats going on?
Click to Flip
As the problem says the apprentice mixed up the hands so that the minute hand was short and the hour hand was long.
The first time the apprentice returned to the client was about 2 hours and 10 minutes after he had set the clock at six.The long had moved olny from twelve to a little past two. The little made two whole circles and an additional 10 minutes. Thus the clock showed the correct time.
The next day around 7:o5 a.m.he came a second time,13 hours and 15 minutes after he had set the clock for six. The long had, acting as the hour hand,covered 13 hours to reach 1. The short hand made 13 full circles and 5 minutes, reaching 7, So the clock showed the correct time again.

Math riddles

A woman went into a bank to cash an insurance refund check. By mistake the teller gave her dollars for cents and cents for dollars. She put the money in her purse but accidentally dropped a nickel on the floor. When she got home, she found that she had exactly twice the amount of the check she had cashed. She didn't have any money in her wallet before going to the bank. What was the exact amount of that check?
Click to Flip
The amount must have been $31.63. She received $63.31. After she dropped a nickel there would remain the sum of $63.26, which is twice the amount of the check.

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Math riddles

A hunter met two shepherds, one of whom had three loaves and the other, five loaves. All the loaves were the same size. The three men agreed to share the eight loaves equally between them. After they had eaten, the hunter gave the shepherds eight bronze coins as payment for his meal. How should the two shepherds fairly divide this money?
Click to Flip
The shepherd who had three loaves should get one coin and the shepherd who had five loaves should get seven coins. If there were eight loaves and three men, each man ate two and two-thirds loaves. So the first shepherd gave the hunter one-third of a loaf and the second shepherd gave the hunter two and one-third loaves. The shepherd who gave one-third of a loaf should get one coin and the one who gave seven-thirds of a loaf should get seven coins.

Math riddles

An item is made from lead blanks in a lathe shop. Each blank suffices for 1 item. Lead shavings accumulated for making 6 items can be melted and made into a blank. How many items can be made from 36 blanks?
Click to Flip
From 36 blanks there are 36 items made. The lead shavings are enough to make 6 blanks. Which make 6 more items. But don't stop here. The new shavings are good for 1 more item. Total: 43.

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Math riddles

Two cyclists began a training run, one starting from Moscow and the other starting from Simferopol.
When the riders were 180 miles apart, a fly took an interest. Starting on one cyclists shoulder, the fly flew ahead to meet the other cyclist. After reaching him the fly then turned around and yet back.�
The restless fly continued to shuttleback and fourth until the pair met; then settled on the nose of one rider.
The flys speed was 30 mph. Each cyclist speed was 15 mph.
How many miles did the fly travel?
Click to Flip
The cyclists took 6 hours to meet. The fly traveled 6*30=180 miles.

Math riddles

My age today is three times what it will be three years from now minus three times what my age was three years ago. How old am I?
Click to Flip
Don't be too confused, the answer is 18 years old.

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Math riddles

A bird has a head 9cm long. The tail is equal to the size of the head plus a half of the size of the body. The body is the size of the head plus the tail.
How long is the bird?
Click to Flip
72cm. Th head is 9cm. The tail is 18 + 9= 27cm. The body is 9 + 18 + 9= 36cm. 9 + 27 + 36= 72cm.

Math riddles

If a stopper and a bottle cost $2.10 and the bottle costs $2.00 more than the stopper.
Then what does the stopper cost?
Click to Flip
Five Cents.

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Math riddles

When Gwen is twice as old as Dean, Then I shall be just 17. But Gwendoline was 23 When Dean was twice as old as me.' Thats what Bill said.
So tell us then, How old he was when Dean was ten?
Click to Flip
Eight.

Math riddles

You have accidently left out the plug and are attempting to fill the bath with both taps full on. The hot tap takes 6 minutes to fill the bath. The cold tap takes 2 minutes and the water empties through the plug hole in 4 minutes.
In how many minutes will the bath be filled?
Click to Flip
2 minutes and 24 seconds.

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Math riddles

A car's odometer shows 72927 miles, a palindromic number. What are the minimum miles you would need to travel to form another?
Click to Flip
110 miles. (73037)

Math riddles

A man had a bar of lead that weighed 40 lbs., and he divided it into four pieces in such a way as to allow him to weigh any number of pounds from one to forty. What are the weights of the four pieces?
Click to Flip
1, 3, 9, 27, are the weights of the four pieces.

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Math riddles

A box of hardware contains nuts and bolts.� The bolts account for 25 percent of the number of items in the box.� What percentage are the bolts of the entire box.
Click to Flip
20 percent. For example, there are 10 bolts.� Since the number of bolts is 25 percent of the number of items, there must be 40 nuts. The total number of items = 10 bolts + 40 nuts = 50.� So, 10/50 = 1/5 = 20%.

Math riddles

A man bumps into his mathematician friend on the street that he hasn't seen in 5 years. The man asks the mathematician how old his children are. The mathematician, who always replies in riddles said, "I now have three children. The sum of their ages is equal to the number of windows on the building in front of you and the product of their ages equals 36." The friend then says "I need one more piece of information." The mathematician then replies "My youngest child has blue eyes." What are the ages of the mathematicians three children?
Click to Flip
They are 6, 6, and 1.

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Math riddles

Walking home one day, you take a short cut along the train tracks. The tracks cross a narrow bridge over a deep gorge. At the point you are 3/8 of the way across the bridge, you hear the train whistle somewhere behind you. You charge across the bridge, and jump off the track as the train is about to run you down. As it happens, if you had gone the other way, you would have reached safety just before being run over as well. If you can run ten miles per hour, how fast is the train moving?
Click to Flip
The train is moving at 40 miles per hour. Imagine that a friend is walking with you. When the train whistle blows, you head away from the train, he heads toward it. When he reaches safety, you will be 6/8 (or 3/4)of the way across the bridge, and the train will have just reached the bridge. For the train to cross 4/4 of the bridge in the time you cross the remaining 1/4, the train must be moving four times your speed.

Math riddles

Charlotte is 13 years old. Her father Montague is 40 years old. How many years ago was Charlotte's father four times as old as Charlotte?
Click to Flip
Four years ago. When Charlotte was 9 her father was 36, 4 times her age.

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Math riddles

A book costs $1 plus half its price. How much does it cost?
Click to Flip
$2

Math riddles

What is 1/2 of 1/4 of 2/9 of 3/7 of 84?
Click to Flip
The answer is 1. 3/7 of 84 = 36 2/9 of 36 = 8 1/4 of 8 = 2 1/2 of 2 = 1

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Math riddles

A man told his son that he would give him $1000 if he could accomplish the following task. The father gave his son ten envelopes and a thousand dollars, all in one dollar bills. He told his son, "Place the money in the envelopes in such a manner that no matter what number of dollars I ask for, you can give me one or more of the envelopes, containing the exact amount I asked for without having to open any of the envelopes. If you can do this, you will keep the $1000." When the father asked for a sum of money, the son was able to give him envelopes containing the exact amount of money asked for. How did the son distribute the money among the ten envelopes?
Click to Flip
The contents or the ten envelopes (in dollar bills) should be as follows: $1, 2, 4, 8, 16, 32, 64, 128, 256, 489. The first nine numbers are in geometrical progression, and their sum, deducted from 1,000, gives the contents of the tenth envelope.

Math riddles

When the celebrated German mathematician Karl Friedrich Gauss (1777-1855) was nine he was asked to add all the integers from 1 through 100. He quickly added 1 to 100, 2 to 99, and so on for 50 pairs of numbers each adding to 101.
Answer: 50 X 101=5,050.
Now find the sum of all the digits in integers from 1 through 1,000,000,000.
That's all the digits in all the numbers, not all the numbers themselves.
Click to Flip
The numbers can be grouped by pairs:
999,999,999 and 0;
999,999,998 and 1'
999,999,997 and 2;
and so on....
There are half a billion pairs, and the sum of the digits in each pair is 81. The digits in the unpaired number, 1,000,000,000, add to 1. Then:
(500,000,000 X 81) + 1= 40,500,000,001.

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Math riddles

You go to the doctor because you're ill and he prescribes you with 3 pills and tells you to take them every half hour.
How long do the pills last you?
Click to Flip
An hour because the first pill doesn't take 30 min. to take.

Math riddles

A boy has as many sisters as brothers, but each sister has only half as many sisters as brothers.
How many brothers and sisters are there in the family?
Click to Flip
Four brothers and three sisters.

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Math riddles

A large truck is crossing a bridge 1 mile long. The bridge can only hold 14000 lbs, which is the exact weight of the truck. The truck makes it half way across the bridge and stops. A bird lands on the truck. Does the bridge collapse?
Click to Flip
No, it does not collapse. Because it has driven a half mile - you would subtract the gas used from the total weight of the truck.

Math riddles

Robert and David were preparing to have a water balloon fight. "No Fair" cried Robert, "You have 3 times as many as I do!" David said "Fine!" and gave Robert 10 more balloons. "Still not fair!" argued Robert, "You still have twice as many as I do." How many more balloons must David give Robert for them to have the same number?
Click to Flip
David must give Robert another 20 water balloons, giving them each 60. Robert started with 30 water balloons and David with 90.

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Math riddles

Out of 100 ladies attending the gala,
85 had a white hand bag;
75 had black shoes;
60 carried an umbrella;
90 wore a ring;
How many ladies must have had all four items?
Click to Flip
10
Divide by 3. All the ladies had three items. The remainder shows the number of ladies who had 4.
85
75
60
90
______
310 / 3 = 100 + 10 remainder

Math riddles

Can you divide the watch face with 2 straight lines so that the sums of the sums of the numbers in each part are equal?
Click to Flip
The sum of the numbers on the watch face is 78. If the two lines cross, there must be 4 equal parts, but 78 is not divisible by 4. Then the lines do not cross, giving three parts with the sum of 26 each. Once you see the pairs on the face that add to 13(12+1,11+2, and so far) the answer will be easy to find.

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Math riddles

Jenna wrote all the numbers from 300 to 400 on a piece of paper. How many times did she write the digit 3?
Click to Flip
Jenna wrote it 120 times.

Math riddles

Twelve flags stand equidistant along the track at the stadium. The runners start at the first flag. A runner reaches the eighth flag 8 seconds after he starts. If he runs at an even speed, how many seconds does he need altogether to reach the twelfth flag?
Click to Flip
Not 12 seconds. There are 7 segments from the first flag tot the eighth, and 11 from the first to the twelfth. He runs each segment in 8/7 seconds; therefore, 11 segments take 88/7= 12 4/7 seconds.

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Math riddles

If you toss a die and it comes up with the number one 9 times in a row, what is the probability that it will come up with one on the next throw?
Click to Flip
One in six. A die has no memory of what it last showed.

Math riddles

How much is this bag of potatoes?' asked the man. '32lb divided by half its own weight,' said the green grocer.
How much did the potatoes weigh?
Click to Flip
8lbs.

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Math riddles

Given two 2s, "plus" can be changed to "times" without changing the results: 2 + 2= 2 x 2.
The solution with three numbers is easy too: 1 + 2 + 3= 1 x 2 x 3.
Now find the answer for 4 numbers and for 5 numbers.
Click to Flip
Solution for 4 numbers:
1 + 1 + 2 + 4= 1 x 1 x 2 x 4.
Solution for 5 numbers:
1 + 1 + 1 + 2 + 5= 1 x 1 x 1 x 2 x 4�
1 + 1 + 1 + 3 + 3= 1 x 1 x 1 x 2 x 4
1 + 1 +2 + 2 + 2= 1 x 1 x 2 x 2 x 2

Math riddles

What number is that, which, added separately to 100 and 164, shall make them perfect squares?
Click to Flip
125.

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Math riddles

When I asked her how old she was, she smiled and said cryptically: "The day before yesterday I was 22, but next year I'll be 25." What is her birthday and when was the date of our conversation?
Click to Flip
We conversed on January 1 and her birthday was on December 31. So, the day before yesterday on Dec. 30th she was 22 and he turned 23 on Dec. 31. So her next birthday, when she turns 24, would be Dec. 31 of the same year the question was asked.� However, next years birthday would be the following year on Dec. 31, when she would be 25.

Math riddles

A soccer fan, upset by the defeat of his favorite team, slept restlessly. In his dream a goalkeeper was practicing in a large unfurnished room, tossing a soccer ball against the wall and then catching it.
But the goalkeeper grew smaller and smaller and then changed into a ping-pong ball while the soccer ball was swelled up into a huge cast-iron ball. The iron ball circled round madly, trying to crush the ping-pong ball, how did the ping-pong find safety whithout leaving the floor?
Click to Flip
If the ping-pong ball rolls flush against the wall, the cast-iron ball cannot crush it.
Those who know geometry can determine that if the diameter of a large ball is at least 5.83 (3+2(square root of 2) times as large as the diameter of a little ball, then the little ball will be safe if it hugs the wall.
A cast-iron ball that is larger than a soccer ball is more than 4.83 times as large in diameter as a ping-pong ball.

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Math riddles

A mother has three sick children. She has a 24-ounce bottle of medicine and needs to give each child eight ounces of the medicine. She is unable to get to the store and has only three clean containers, which measure 5, 11 and 13 ounces. The electricity is out and she has no way of heating water to wash the containers and doesn't want to spread germs. How can she divide the medicine to give each child an equal portion without having any two children drink from the same container?
Click to Flip
Fill the 5 oz. and 11 oz. Containers from the 24 oz. container. This leaves 8 oz. in the 24 oz. bottle. Next empty the 11 oz. bottle by pouring the contents into the 13 oz. bottle. Fill the 13 oz. bottle from the 5 oz. container (with 2 oz.) and put the remaining 3 oz. in the 11 oz. bottle. This leaves the 5 oz. container empty. Now pour 5 oz. from the 13 oz. bottle into the 5 oz. bottle leaving 8 oz. in the 13 oz. bottle. Finally pour the 5 oz. bottle contents into the 11 oz. bottle giving 8 oz. in this container.

Math riddles

How many pluses should we put between the digits of 987,654,321 to get a total of 99, and where?
Click to Flip
(6) 9 + 8 + 7 + 6 + 5 + 43 + 21= 99
(7) 9 + 8 + 7 + 65 + 4 + 3 + 2 + 1= 99

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Math riddles

(A) Use two digits to make the smallest possible positve intiger.
(B) Five 3s can express 37: �37=33+3+3/3
Find another way to do it.
(C) Use six identical dgits to make 100. (Several solutions are possible.)
(D) Use five 4s to make 55.
(E) Use four 9s to make 20.
Click to Flip
(A) 1 X 1; 1/1;2/2;ect....;1-0;2-1;and many others.
(B) 37=333/3X3; 37=3 X 3 X 3 + 3/.3
(C) 99 + 99/99; 55+55- 5- 5; (666-66)/6
(D) 44 + 44/4=55.
(E) 9 + 99/9=20.

Math riddles

Mr. and Mrs. Smith were walking home from the shopping mall with their purchases when Mr. Smith began to complain that his load was too heavy. Mrs. Smith turned to her husband and said, "I don't know what you're complaining about because if you gave me one of your parcels, I would have twice as many as you and if I gave you just one of mine, we would have equal loads." How many parcels was each carrying?
Click to Flip
Mrs. Smith was carrying seven parcels and Mr. Smith was carrying five.

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Math riddles

2, 3, 5, 9, 17, _ What is the next number in the sequence?
Click to Flip
33. The pattern:� Double the previous number and subtract 1.

Math riddles

Edward is as old as Benjamin used to be when Edward was as old as Benjamn is now.
Benjamin is 36. How old is Edward?
Click to Flip
Edward is 48.

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Math riddles

An officer wishing to arrange his men in a solid square found by his first arrangement that he had 39 men left over. He then started increasing the number of men on a side by one, but found that 50 additional men would be needed to complete a new square.
How many men did the officer have?
Click to Flip
The officer had 1975 men. When he formed a square measuring 44 by 44, he had 39 men over. When he tried to form a square 45 x 45, he was 50 men short.

Math riddles

Insert the numbers 1-9 inclusive each only, into the claculation to arrive at the answer 100.
( �- �) �+ �+ �- �- �- �= �100
Click to Flip
( 7 - 5 )�� + 96 + 8 - 4 - 3 - 1 = 100

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Math riddles

A house has 6 stories, each the same height. How many times as long is the ascent to the sixth floor as the ascent to the third?
Click to Flip
2 1/2 times (5/2, not 6/3).

Math riddles

Find four numbers, the sum of which is 45, so that if 2 is added to the first number, 2 is subtracted from the second number, the third number is multiplied by 2 and the fourth number is divided by 2, then the four numbers so produced are all the same. What are the four numbers?
Click to Flip
8 + 2 = 10
12 - 2 = 10
� 5 x 2 = 10
20 � 2 = 10
45

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Math riddles

If 6 doubloons are worth 1 1/2 ducats, how many ducats are 27 doubloons worth?
Click to Flip
6 3/4 ducats (27/6=4 1/2. 4 1/2 x 1 1/2= 6 3/4)

Math riddles

Farmer Brown came to town with some watermelons. He sold half of them plus half a melon, and found that he had one whole melon left. How many melons did he take to town?
Click to Flip
Three melons!

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Math riddles

Lazy Larry agreed to work on a job for his brother-in-law for thirty hours at eight dollars an hour, on the condition that he would forfeit ten dollars per hour for every hour that he idled. At the end of the thirty hours Larry wasn't owed any money and didn't owe his brother-in-law any money either. How many hours did Larry work and how many hours did he idle?
Click to Flip
Lazy Larry worked 16-2/3 hours and idled 13-1/3 hours. 16-2/3 hours, at $8.00 an hour amounts to the same amount as 13-1/3 hours at $10.00 per hour.

Math riddles

A woman is walking down a street night at a constant pace.� As she passes the street light, she notices that her shadow becomes longer.� Does the top of her shadow move faster, slower or the same when the shadow is longer as when it is shorter?
Click to Flip
This point maintains a constant speed, independent of the lenght of the shadow.

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Math riddles

Two travellers spend from 12 o'clock to 6 o'clock walking along a level road, up a hill and back again. Their pace is 4 mph on the level, 3 mph uphill, and 6 mph downhill.
How far do they walk and at what time do they reach the top of the hill?
Click to Flip
24 miles half past three.

Math riddles

0,1,2,3,4,5,6,7,8,9
Use the digits above once each only to compose two fractions which when added togeather equal 1.
Click to Flip
35/70 + 148/296 = 1

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Math riddles

A half is a third of it. What is it?
Click to Flip
1 1/2.

Math riddles

If it is 1,800 kilometers to America, 1,200 kilometers to Japan, 2,400 kilometers to New Zealand, and 1,400 kilometers to Brazil-�
How far is Morocco?
Click to Flip
The answer is 1,700 kilometers, as vowels in the countries' names are worth 300 kilometers and the consonats are worth 200 kilometers.

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Math riddles

It takes the town hall clock 6 seconds to strike 4 o'clock in the afternoon. How long does it take to strike midnight?
Click to Flip
22 Seconds.

Math riddles

How many times does the long hand of the clock pass the short hand between midnight one day and midnight the following day? As both hands are together at the starting time of midnight this does not count as a pass.
Click to Flip
21.

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Math riddles

An alarm clock runs 4 minutes slow every hour. It was set right 3 1/2 hours ago. Now another clock which is correct shows noon.�
In how many minutes, to the nearest minutes, to the nearest minute, will the alarm clock show noon?
Click to Flip
In 3 1/2 hours the alarm clock has become 14 minutes slow. At noon the alarm clock will fall behind approximently an additional minute. Its hands will show noon in 15 minutes.

Math riddles

The title of the problem tells you how to approach these four questions.
(A). �A bus leaves Moscow for Tula at noon. An hour later a cyclist leaves Tula for mosco, moving slower than the bus. When the bus and cyclist meet, which one of the two will be farther from Moscow?
(B). Which is worth more: a pound of $10 gold peices or half a pound of $20 gold pieces?
(C). At six o'clock the wall clock struck 6 times. Checking with my watch, I noticed the time between the first and last strokes was 30 seconds. How long will the clock take to strike 12 at midnight?
(D). Three swallows fly outward from a point. When will they all be on the same plane in space?
Now check the answers. Did you fall into any of the traps which lurk in these simple problems?
Click to Flip
(A). Neither
(B). A pound of metal is always more than half a pound of the same metal.
(C). Six strokes took 30 seconds, therefore 12 strokes will take 60 seconds. But when the clock struck six, there were only 5 intervals between strokes, and each interval was 30/5=6 seconds. Between the first and twelfth strokes there will be 11 intervals of 6 seconds each, therefore 12 strokes will take 66 seconds.
(D). There is always a plane that contains any 3 points

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Math riddles

Mr. Grumper grumbles about bad time-keeping trains like everybody else. On one particular morning he was justified, though. The train left on time for the one hour journey and it arrived 5 minutes late. However, Mr. Grumper's watch showed it to be 3 minutes early, so he adjusted his watch by putting it forward 3 minutes. His watch kept time during the day, and on the return journey in the evening the train started on time, according to his watch, and arrived on time, according to the station clock. If the train traveled 25 percent faster on the return journey than it did on the morning journey, was the station clock fast or slow, and by how much?
Click to Flip
The station clock is 3 minutes fast. The morning journey took 65 minutes, and the evening journey therefore took 52 minutes, and the train arrived 57 minutes after it should have left, that is, 3 minutes early.

Math riddles

Two wine merchants arrive at the gates of Paris. One has 64 and the other 20 barrels of wine. Since they have not enough money to pay the custom duties, the first pays 40 francs and 5 barrels of wine. The second pays 2 barrels of wine but receives 40 francs in change.
What is the value of each barrel of wine and what is the duty payable?
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The value of a barrel is 120 francs and the duty is 10 francs a barrel.

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Math riddles

How can you give someone $63 using six bills, without using any one dollar bills?
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1 - $50 bill, 1 - $5 bill , 4 - $2 bills

Math riddles

What number squared = 12345678987654321?
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111,111,111

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Math riddles

What single-digit number should go in the box with the question?
6 5 9 2 7
1 4 3 5 ?
8 0 2 8 1
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The missing number is 4.� Simply add the first and second rows together to get the third row value.
� 65, 927
+ 14, 354
� 80, 281

Math riddles

Jack has 8 bricks 7 of them weights the same amount and one is slightly heavier. Using a balance scale, how can Jack find the heavier brick in two weighings?
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First he split them in to piles of 3, 3, and 2 bricks. Then he weighs both groups of 3 with each other. If they balance he knows the brick is one of the 2 unweighed bricks and he can weigh them to find the heaver one. If the the stacks of 3 bricks do not balance, he will weigh 2 of the 3 bricks. If they balance he will know the brick left unweighed is heavier, or if they do not balance, he will find the heavier one.

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Math riddles

This number added to it's square, and the digits of that summation added together, bring it back to itself. What is it?
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3. 3 squared is 9. 3+9=12. Take the two digits of the summation and add them; 1+2=3. In short; 3-9-12-3. This can also work with the number 0 and 9.

Math riddles

If seven cats kill seven rats in 7 minutes, how many would be needed to kill one hundred rats in 50 minutes?
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14.

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Math riddles

Jack had only $2, but he needed $3 for his cab fare home. He went to a pawn shop and pawned his $2 for $1.50. Jack then bumped into Don and told him that he would sell him his $2 pawn ticket for $1.50. Don agreed. Jack started out with $2 and he ended up with $3. Who is out the extra dollar and why?
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Don is out the extra dollar. Before the pawn broker will return the $2 to the ticket holder, he will want the $1.50 which he advanced returned to him. Don will give the pawn broker the ticket and the $1.50, and the pawn broker will then return the $2.

Math riddles

How many sides does a snowflake have?
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6.

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Math riddles

You are given a set of scales and 12 marbles. The scales are of the old balance variety. That is, a small dish hangs from each end of a rod that is balanced in the middle. The device enables you to conclude either that the contents of the dishes weight the same or that the dish that falls lower has heavier contents than the other. The 12 marbles appear to be identical. In fact, 11 of them are identical, and one is of a different weight. Your task is to identify the unusual marble and discard it. You are allowed to use the scales three times if you wish, but no more. Note that the unusual marble may be heavier or lighter than the others. You are asked to both identify it and determine whether it is heavy or light
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Most people seem to think that the thing to do is weight six coins against six coins, but if you think about it, this would yield you no information concerning the whereabouts of the only different coin. As we already know that one side will be heavier than the other. So that the following plan can be followed, let us number the coins from 1 to 12. For the first weighing let us put on the left pan coins 1,2,3,4 and on the right pan coins 5,6,7,8. There are two possibilities. Either they balance, or they don't. If they balance, then the different coin is in the group 9,10,11,12. So for our second weighing we would put 1,2 in the left pan and 9,10 on the right. If these balance then the different coin is either 11 or 12. Weigh coin 1 against 11. If they balance, the different coin is number 12. If they do not balance, then 11 is the different coin. If 1,2 vs 9,10 do not balance, then the different coin is either 9 or 10. Again, weigh 1 against 9. If they balance, the different coin is number 10, otherwise it is number 9. That was the easy part. What if the first weighing 1,2,3,4 vs 5,6,7,8 does not balance? Then any one of these coins could be the different coin. Now, in order to proceed, we must keep track of which side is heavy for each of the following weighings. Suppose that 5,6,7,8 is the heavy side. We now weigh 1,5,6 against 2,7,8. If they balance, then the different coin is either 3 or 4. Weigh 4 against 9, a known good coin. If they balance then the different coin is 3, otherwise it is 4. Now, if 1,5,6 vs 2,7,8 does not balance, and 2,7,8 is the heavy side, then either 7 or 8 is a different, heavy coin, or 1 is a different, light coin. For the third weighing, weigh 7 against 8. Whichever side is heavy is the different coin. If they balance, then 1 is the different coin. Should the weighing of 1,5, 6 vs 2,7,8 show 1,5,6 to be the heavy side, then either 5 or 6 is a different heavy coin or 2 is a light different coin. Weigh 5 against 6. The heavier one is the different coin. If they balance, then 2 is a different light coin.

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Math riddles

My only timepiece is a wall clock. One day I forgot to wind it and it stopped. I went to visit a friend whos watch is always correct, stayed awhile, and then went home. There I made a simple calculation and set the clock right.
How did I do this even though I had no watch on me to tell how long it took me to return from my friend's house?
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Before I left, I wound the wall clock. When I returned, the change in time equaled how long it took to go to my friends house and return, plus the time I spent there. But I knew the latter because I looked at my friends watch when I arrived and left.
Subtracting the time of the visit from the time I was absent from my house, and dividing by 2, I obtained the time it took me to return home. I added this time to what my friend watch showed when I left, and set the sum on my wall clock.

Math riddles

A man has nine children, born at regular intervals. The sum of their squares of their ages is equal to the square of his own age.
What are �the ages of the children?
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2 �- �5 �- �8 �- �11 �- �14 �- �17 �- �20 �- �23 �- �26

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Math riddles

How many cats are in a small room if in each of the four corners a cat is sitting, and opposite each cat there sit three cats, and a each cat's tail another is sitting?
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Four cats, each near a tail of a cat in an adjacent corner.

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