Calculating Squares

Here is a "quick" (depends on how quick you are) of calculating squares.

Assume that the number you want to calculate is 47 X 47 [47 times 47].

Then, take 50 times 50 = 2500
minus 50 times 2 times (50-47) = 50 X 2 X 3 = 300
plus (50-47) squared = 3 X 3 = 9

Hence, ans: 2500 - 300 + 9.

You should be able to figure how it works for other numbers...