Q. Find whether each of the following numbers is a perfect square or not?
(ii) 55
If it is a sum of successive odd natural numbers starting with 1, then it is a perfect square.
So we try to express 55 in successive integers. This can also be done by subtracting successive odd natural numbers from 55.
55 - 1 = 54 ; 54 - 3 = 51 ; 51 - 5 = 46 ; 46 - 7 = 39 ; 39 - 9 = 30 ; 30 - 11 = 19 ; 19 - 13 = 6.
Thus 55 is not a perfect square.