If you multiply my age three years from now by my age three years ago, the resulting product is exactly 72. How old am I today?
9 years old
Let age be X. (X + 3) * (X - 3) = 72. This is X^2 - 9 = 72, so X^2 = 81. Since age must be a positive number, X = 9.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Medium. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
More logic riddles
The snowball is smaller than the icicle, and the icicle is smaller than the mitten. Which one is the biggest?
Five light bulbs numbered 1 to 5 are all initially turned off. Switch 1 toggles bulb 1. Switch 2 toggles bulbs 1 and 2. Switch 3 toggles bulbs 1, 2, and 3, and so on up to Switch 5. If you flip Switch 2, then Switch 4, then Switch 5, which bulbs remain ON?
If five machines can make five widgets in exactly five minutes, how many minutes would it take one hundred machines to make one hundred widgets?
Four runners—Sam, Alex, Jordan, and Taylor—finished a race in four different positions. Sam finished before Alex. Jordan finished after Taylor. Alex finished before Jordan. Who won the race?
An ancient vault requires a four-digit numeric code. - The first digit is double the last digit. - The second digit is the sum of the first and last digits. - The third digit is half of the second digit. - The sum of all four digits is 18. What is the code?
A row goes: icicle, icicle, snowball, icicle, icicle, snowball, icicle, icicle. What comes next?