Question

Which of the following number  square of even number? 

1296 

Answer 1

The numbers whose last digit is odd can never be the square of even number. 

use prime factorisation method and make pairs of equal factors. 

1296 = 2 x 2 x 2 x 2 x 3 x 3 x 3 x 3
                 = (2 x 2) x (2 x 2) x (3 x 3) x (3 x 3)
There are no factors that are not paired. Hence, 1296 is a perfect square. The square of an even number is always even. Hence, 1296 is the square of an even number.