Replace the question mark with the correct number.

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

A doctor and a boy were fishing. The boy was the doctor’s son, but the doctor was not the boy’s father. Who was the doctor?

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain

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?

What do you see in the given picture?

I can write cow in 13 letters.

Can You?

Can you place six X (crosses) in below board without making three in a row in any way ?

Which three-digit number, made of consecutive digits, like 567, is 2 less than a cube and 2 more than a square?

John has played 50 ODI's and his average is 50. How many runs should he score in his 51st ODI, so that his average score jumps to 51?