A frog is at the bottom of a 30-meter well. Each day he summons enough energy for one 3-meter leap up the well. Exhausted, he then hangs there for the rest of the day. At night, while he is asleep, he slips 2 meters backwards. How many days does it take him to escape from the well?

What four weights can be used to balance from 1 to 30 pounds?

There is one four-digit whole number n, such that the last four digits of n2 are the original number n

Solve the mathematical equation in the picture below.

What breaks yet never falls, and what falls yet never breaks?

When can we add 2 to 11 and get 1 as the correct answer?

Why do Chinese men eat more rice than Japanese men do ?

How many triangles can you count in the figure given?

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

I’m tall when I’m young, and I’m short when I’m old. What am I?