How to Square numbers made up of repeating ‘3’ mentally in 2 seconds

This is cool and all, but I don't see how it's useful. It's a very narrow algorithm that you might use once and a while.

On the other hand, this is a perfect example of mathematical beauty.

square(333) is the addition of 999 + 9990 + 99900 = (1000 - 1) + (10000 - 10) + (100000 - 100) = 111000 - 111

The more '3' you add, the more '1' and '0' you get. square(333) = 11110000 - 1111

It is actually a very binary computing.

title should read:

How to Square numbers made up of repeating ‘3’ mentally in 3 seconds

just so much catchier. OTOH, link-bait title would read "How three Indian university students came up with..."