To find square of a number ending in ‘5’

With this trick you can find the square of all numbers having ‘5’ as the last digit.

Short trick:

(Left) x (Left +1)|25

 

Example:

 Let’s find the square of 75.

Solution:

Here last digit is 5 and left part is 7.

By using above formula we have-
(Left)x(Left + 1)|25
= (7)x(7+1)|25
= 7x8|25
= 56|25
= 5625

 

Example:

Find the square of 205.

Solution:

Here last digit is 5 and left part is 20.

By using above formula we have-

(Left)x(Left + 1)|25
= (20)x(20+1)|25
= 20x21|25
= 420|25
= 42025