

Largest 2 digit number is 99
Now, we will find the square root of 99, we get 18 as remainder.
Now whatever number which is remaining at the last we will subtract it from 99
18 is remaining at the last, So when we subtract it from 99
i.e. 99 - 18 = 81
So, the largest 2 digit number which is a perfect square is 81
