Can you find out which number multiplied by itself will give the output as 12345678987654321?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

I am a number I am not an odd number I am higher than 90 I am not higher than 100 If you subtract me from 100, you get nothing. What number am I?

Can you find the ages of a son, father and grandfather based on the following facts?
The sum of the ages of grandfather, father and son is 140 years.
The age of the son in months is the same as the grandfather in years.
The age of the son in days is the same as the father in weeks.

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

Get total of 120 by using five zeros 0,0,0,0,0 and any one mathematical operator.
Do you ?

If 21x = 79x, what is the value of x?

If in a car race, the man who came two places in front of the last man finished one ahead of the man who came fifth, how many contestants were there?

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

Solve the mathematical equation in the picture below.