Without doing any calculation, find the numbers which are surely not perfect squares.

(i) 153 (ii) 257

(iii) 408 (iv) 441

The perfect squares of a number may end with any of the following digits at unit's place:

0, 1, 4, 5, 6, or 9

And, a perfect square will end with even number of zeroes

(i) Since the unit place digit of number 153 is 3, hence it is not a perfect square

(ii) Since the unit place digit of number 257 is 7, hence it is not a perfect square

(iii) Since the number 408 has its unit place digit as 8, it is not a perfect square

(iv) Since the number 441 has its unit place digit as 1, it is a perfect square