Math Riddles

There are 500 coffins and 500 men who need them. The undertaker asks the first man to go to every coffin and open them. Then he tells the second man to go to every one and close it. The third one goes to every third coffin and so on. How many are open?

123=0
4235=0
656=2
5390=2
8890=6
1001=2
19235=1
What is 123456789?

How do you go from 98 to 720 using just one letter?

I am a number with a couple of friends, quarter a dozen, and you'll find me again.
What am I?

Add me to myself and multiply by 4.
Divide me by 8 and you will have me once more.
What number am I?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

There is a three digit number.
The second digit is four times as big as the third digit, while the first digit is three less than the second digit.
What is the number?

How many 9's are there between 1 and 100?

In two years I know, I'll be twice as old as five years ago, said Tom. How old is Tom?

What is half of two plus two?

Mom and dad have four daughters, and each daughter has one brother.
How many people are in the family?

Four years ago, Alex was twice as old as Jake. Four years from now, Jake will be 3/4 of Alex's age. How old is Alex?

If it is two hours later, then it will take half as much time till it's midnight as it would be if it were an hour later. What time is it?

Sally is 54 years old and her mother is 80, how many years ago was Sally's mother three times her age?

If two hours ago, it was as long after one o'clock in the afternoon as it was before one o'clock in the morning, what time would it be now?

I am four times as old as my daughter. In 20 years time I shall be twice as old as her. How old are we now?

An apple is 40 cents, a banana is 60 cents and a grapefruit is 80 cents. How much is a pear?

If you're 8 feet away from a door and with each move you advance half the distance to the door. How many moves will it take to reach the door?

In a bicycle race, the man who came two places in front of the last man finished one ahead of the man who came fifth. How many contestants were there?

My daughter has many sisters. She has as many sisters as she has brothers. Each of her brothers has twice as many sisters as brothers. How many sons and daughters do I have?

When my father was 31 I was 8.
Now he is twice as old as me.
How old am I?

What did one math book say to another?

One brick is one kilogram and half a brick heavy. What is the weight of one brick?

Place three matches on a table. Tell a friend to add two more matches to make eight.

There are 25 red balls, 47 green balls and 3 blue balls in a basket. There is a blind man. What is the minimum number of balls that the blind man has to pick to make sure that there are at least 2 balls of different colors?

Use the numbers 2, 3, 4 and 5 and the symbols + and = to make a true equation.

Mr. Smith has 4 daughters.
Each of his daughters has a brother.
How many children does Mr. Smith have?

You have 14 brown socks, 14 blue socks and 14 black socks in your sock drawer. How many socks must you remove (without looking to be sure) to have a matched pair?

How can you add eight 8's to get the number 1000?

Three times what number is no larger than two times that same number?

If you go to the movies and you're paying, is it cheaper to take one friend to the movies twice, or two friends to the movies at the same time?

The combined age of Jack and John is 49. Jack is twice as old, as John was when Jack was as old as John is now. How old are the brothers?

How many days are there in 4 years?

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 1000?

If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take for the patch to cover half the lake?

Dean Sam and Castiel are three brothers. Interestingly their current age is prime. What's more interesting that difference between their ages is also prime. How old are they?

What do mathematics teachers like to eat?

Joe has ten coins totaling $1.19. From these coins, he cannot make exact change for a dollar, half-dollar, quarter, dime, or nickel.
What are the coins?

There are two fathers and two sons. They walk into a candy store and each buys a candy bar for 50 cents. The total for all of the candy bars was $1.50. How is that possible?

What number do you get when you multiply all of the numbers on a telephone's number pad?

How can you give someone $83 using exactly 7 bills, without using any one dollar bills?

If Mr. Flynn is 90 centimeters plus half his height, how tall is he?

Divide 20 by half and add 30, what do you get?

There are 12 kids in a classroom. 6 kids are wearing socks and 4 are wearing shoes. 3 kids are wearing both. How many are bare feet?

When I take five and add six, I get eleven, but when I take six and add seven, I get one. What am I?

A bat and a ball cost $1.10. The bat costs one dollar more than the ball. How much does the ball cost?

What 3 positive numbers give the same result when multiplied and added together?

When is 1500 plus 20 and 1600 minus 40 the same thing?