Question

Which of the following number  square of even number?

324 

Answer 1

The numbers whose last digit is odd can never be the square of even numbers  use prime factorisation method and make pairs of equal factors. 

 324 = 2 x 2 x 3 x 3 x 3 x 3
              = (2 x 2) x (3 x 3) x (3 x 3)
There are no factors that are not paired. Hence, 324 is a perfect square. The square of an even number is always even. Hence, 324 is the square of an even number.