- How many times can you subtract the number 5 from 25?
- What number can you subtract half from to obtain a result of zero?
- How is half of nine four?
- What two whole, positive numbers that have a one-digit answer when multiplied and a two-digit answer when added?
- What two whole, positive numbers have the same answer when multiplied together as when one is divided by the other?
- What two whole, postive numbers have the same answer when multiplied together as when added together?
- What two-digit number equals two times the result of multiplying its digits?
- What three whole, positive numbers have the same answer when multiplied together as when added together?
- What two-digit numbers are each equal to their right-most digit squared?
- What is the highest number that can be written with three digits?

- Once, because after you subtract it's not 25 anymore.
- The number 8. It's made up of two zeros, one on top of the other.
- In Roman Numerals, nine is IX and four is IV. If you take IX and cut it in half horizontally, you will get IV.
- 1 and 9.
- Any number and 1.
- 2 and 2.
- 36 = 2 x 3 x 6.
- 1, 2 and 3. 1 x 2 x 3 = 1 + 2 + 3 = 6
- 25 = 5² and 36 = 6².
- (9⁹)⁹ = 9³⁸⁷⁴²⁰⁴⁸⁹, which is a number with more than 369 million digits.