How to find the square of any number ending in 5 ?

Question

For example how to find the squares of 15, 25, 45, 85, 95, 125, 345 and so on.

Answer 1

The Square of any number ending in 5: The last two digits will always be 25. The digits before that in the answer will got by multiplying the digits leading up to the digit 5 in the number by 1 more than itself.
Explanation:
            Suppose we have to find square of 25. Then answer will be got by 2 * (2+1) = 2*3 = 6
Hence the square of 25 = 625