Question

The following numbers are not perfect squares. Give reason
$1057$
$23453$
$7928$

Answer 1

A number that ends either with $2,3,7$ or $8$ cannot be a perfect square. Also, a number that ends with odd number of zero(s) cannot be a perfect square.
As the given numbers end with either $2,3,7$ or $8$, they are not perfect squares.