which of the following is a perfect square : 100856 and 945729 ? Explain the easiest and fastest way of checking it.

Find the digital sum of the numbers given. A perfect square digital sum will always end in 1, 4, 7 or 9. So, 1+0+0+8+5+6 = 20 = 2+0 = 2, so this number is not  a perfect square. whereas 9+4+5+7+2+9 = 36 = 3+6 = 9, so this number is a perfect square. Download number systems formulas for CAT which will help you to learn various important concepts.