When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

A farmer went to a market and bought a wolf, a goat, and a cabbage. On his way home, the farmer came to the bank of a river and rented a boat. But crossing the river by boat, the farmer could carry only himself and a single one of his purchases: the wolf, the goat, or the cabbage. If left unattended together, the wolf would eat the goat, or the goat would eat the cabbage. The farmer’s challenge was to carry himself and his purchases to the far bank of the river, leaving each purchase intact. How did he do it?

What do you see in the given picture?

In the addition below, all digits have been replaced by letters. Equal letters represent equal digits and different letters represent different digits.
ABCABA
BBDCAA
ABEABB
ABDBAA
------- +
AAFGBDH
What does the complete addition look like in digits?

Solve the mathematical equation in the picture below.

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

No matter how little or how much you use me, you change me every month. What am I?

How do you go from 98 to 720 using just one letter?

Place the numbers from 1 to 9 in the circles in a manner that each side of the triangle sums up to 17.

It belongs to you, but other people use it more than you do. What is it?