Given sets of numbers are
25 , 16 , 49 , 63 , 81
We can see 25 is a square of 5 because 5 * 5 = 25
Similarly 16 = 4*4
49 = 7*7
81 = 9*9
But we can not write 63 as a square of any number.
SO we can say 63 is not like the others because we can write other one as a square of any number. But 63 is not a perfect square.
