The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

Using Only Five 5's and any mathematical operator make sum as 37

If we add four times the age of John four years from now to five times his age five years from now we get ten times his current age.

How old will John be two years from now?

A four-digit number (not beginning with 0) can be represented by ABCD. There is one number such that ABCD=A^B*C^D, where A^B means A raised to the B power. Can you find it?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

Replace the 'X' with any mathematical symbol to make the expression equal to 111.

18 X 12 X 2 X 3 = 111

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?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

Find the number of squares in the below-given picture.

A network of 20 x 10 squares is given to you.

Can you calculate how many unique squares and rectangles can be formed combining two or more individual squares ?