Question

The following number is obviously not a perfect square. Give reasons.

1057

Answer 1

The square of any number generally has one of these digits 0, 1, 4, 5, 6 or 9 at its unit place.
Also, a number which is a perfect square may have even number of zeroes at its end.

1057 has its unit place digit as 7. Therefore, it cannot be a perfect square.