Q. How many 4-digit perfect squares can be formed using the digits 1, 2, 5 and 9, without repetition?

TITA type i.e. Type In The Answer type

0

The digit sum of a perfect square is always 1, 4, 7 or 9.

Sum of the digits of the given numbers (1, 2, 5, 9) is 8.

So, there will be no perfect square possible.