Replace the question mark with the correct number in below Picture:

Christina, Allison and Lena are 3 daughters of John a well-known Mathematician, When I asked John the age of their daughters. He replied "The current age of her daughters is prime. Also, the difference between their ages is also prime."

How old are the daughters?

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?

What number divided by 4 is the same as that number minus 4?

I look at you, you look at me I raise my right, you raise your left. What am I?

I have Rs.50 and I spend it in the way as below.

How many letters are in the alphabet?

Find The Next Number in this series.
1, 2, 6, 42, 1806 ?

A new Engineering building containing 100 offices had just been completed. John was hired to paint the numbers 1 to 100 on the doors. How many times will John have to paint the number nine (9)?

Can you divide the below-given shape into four equal and identical pieces?