Math Riddles with Answers
Number riddles and brain teasers. Most need arithmetic, a few need a fresh look at the question. Click “Show the answer” under any riddle, or open it for a hint and to type your guess.
There are three apples and you take away two. How many apples do you have?
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Two. You took two apples, so you have two.
A farmer has 17 sheep, and all but 9 run away. How many are left?
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Nine. “All but 9” means 9 of them stayed.
What do you get if you multiply all the numbers on a phone keypad?
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Zero. The keypad includes 0, and anything multiplied by 0 is 0.
I am an odd number. Take away one letter and I become even. What number am I?
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Seven. Remove the S from “seven” and you get “even”.
How can you add eight 8s to get 1,000?
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888 + 88 + 8 + 8 + 8. 888 + 88 + 8 + 8 + 8 = 1,000.
What is half of two plus two?
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Three. Half of two is one, and one plus two is three.
When I was six, my sister was half my age. Now I am 70. How old is my sister?
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67. She was three years younger then and is still three years younger: 67.
Which is heavier: a pound of feathers or a pound of bricks?
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Neither. A pound is a pound, whatever it is made of.
A bat and a ball cost $1.10 together. The bat costs $1.00 more than the ball. How much is the ball?
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5 cents. If the ball is 5 cents, the bat is $1.05: together $1.10, and the bat costs exactly $1.00 more.
How many sides does a circle have?
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Two, inside and outside. A circle has an inside and an outside.
What comes next: 1, 1, 2, 3, 5, 8, 13…?
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21. Each number is the sum of the two before it, and 8 + 13 = 21.
Which three positive whole numbers give the same result when added together as when multiplied together?
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1, 2 and 3. 1 + 2 + 3 = 6 and 1 × 2 × 3 = 6.
What has six faces and 21 eyes but cannot see?
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A die. A die has six faces, and its dots add up to 1 + 2 + 3 + 4 + 5 + 6 = 21.