With this trick you can find the square of all numbers having ‘5’ as the last digit.
Short trick:
(Left) x (Left +1)|25
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
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