Math Riddles

Are you a math wiz? Find out with these math riddles.

Give them a try and see just how much of a mathematical genius you really are.

Are you a math wiz? Test yourself with these fiendishly difficult math riddles and see just how clever you are.

Using only addition, how can you add eight 8s to get the number 1,000?

888 + 88 + 8 + 8 + 8 = 1,000.

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

1, 2 and 3.

One out of 9 otherwise identical balls is overweight. How can it be identified after 2 weighings?

Weigh a group of 3 balls against another group of 3, then you’ll know which group of 3 contains the heavy ball. Pick 2 balls from that group and weigh one against the other.

If you can purchase 8 eggs for 26 cents, how many can you buy for a cent and a quarter?


The ages of a father and son add up to 66. The father’s age is the son’s age reversed. How old could they be (there are 3 possible solutions)?

42 and 24. 51 and 15. 60 and 6.

Three friends check into a motel for the night and the clerk tells them the bill is $30, payable in advance.

So, they each pay the clerk $10 and go to their room. A few minutes later, the clerk realizes he has made an error and overcharged the trio by $5.

He asks the bellhop to return $5 to the 3 friends who had just checked in. The bellhop sees this as an opportunity to make $2 as he reasons that the three friends would have a tough time dividing $5 evenly among them; so he decides to tell them that the clerk made a mistake of only $3, giving a dollar back to each of the friends.

He pockets the leftover $2 and goes home for the day.

Now, each of the three friends gets a dollar back, thus they each paid $9 for the room which is a total of $27 for the night. We know the bellhop pocketed $2 and adding that to the $27, you get $29, not $30 which was originally spent.

Where did the other dollar go?

There is an initial $30 charge. It should have been $25, so $5 must be returned and accounted for. $3 is given to the 3 friends, $2 is kept by the bellhop – there you have the $5.

The trick to this riddle is that the addition and subtraction are done at the wrong times to misdirect your thinking – and quite successfully for most.

Each of the 3 friends did indeed pay $9, not $10, and as far as the friends are concerned, they paid $27 for the night.

But we know that the clerk will tell us that they were charged only $25 and when you add the $3 returned with the $2 kept by the bellhop, you come up with $30.

Two fathers and two sons go fishing. Each of them catches one fish. So why do they bring home only three fish?

Because the fishing group consists of a grandfather, his son, and his son’s son.

The day before yesterday I was 21 and the next year I will be 24. What day is my birthday?

31st December. It must be the 1st January, when I turned 22 and so 21 the day before. As it is now a new year, I will be 23 this year and so 24 next year.

I am an odd number. Take away a letter and I become even. What number am I?


Peter is 54 years old, and his father Joe is 80. How many years ago was Joe three times the age of his son Peter?

41 years ago.

There are several books on a bookshelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

9 books.

What do you get when you divide 30 by 1/2 and add 10?


I am a three digit number. My tens digit is five more than my ones digit. My hundreds digit is eight less than my tens digit. What number am I?


A snail is at the bottom of a 20 meters deep pit. Every day the snail climbs 5 meters upwards, but at night it slides 4 meters back downwards. How many days does it take before the snail reaches the top of the pit?

The snail reaches the top of the pit on the 16th day. On the first day, the snail reaches a height of 5 meters and slides down 4 meters at night, and thus ends at a height of 1 meter. On the second day, he reaches 6 meters, but slides back to 2 meters. On the third day, he reaches 7 meters, but slides back to 3 meters. On the fifteenth day, he reaches 19 meters, but slides back to 15 meters. On the sixteenth day, he reaches 20 meters, so now he is at the top of the pit.

A man dies of old age on his 25th birthday. How is this possible?

He was born on February, 29th.

I asked a girl how old she was. She said, “In 2 years I will be twice as old as I was 5 years ago.” How old is she?


If it were two hours later, it would be half as long until midnight as it would be if it were an hour later. What time is it now?


A farmer has 17 sheep and all but 9 die. How many are left?


There are two ducks in front of two other ducks. There are two ducks behind two other ducks. There are two ducks beside two other ducks. How many ducks are there?

Four ducks (in a square).

Can you arrange four nines to make it equal to 100.

99+9/9 = 100.

I have two US coins totalling 55 cents. One is not a nickel. What are the coins?

A 50 cent piece and a nickel. The 50 cent piece is the coin is that is not a nickel!

Why should you never mention the number 288 in front of anyone?

Because 288 is too gross. (A gross is 144, so 2 gross is 144 x 2 or 288)

Math Riddles

If you liked these math riddles, check out our other riddles and brainteasers too, including these:

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