Sum of n squares video improvement

Sal's video on sum of n squares was good but it was a difficult job to fully grasp it in the first watch. I found a video on the same on BlackPenRedPen YouTube channel.

https://youtu.be/OpA7oNmHobM

Their method is really easy. So I thought I should tell you. ;-)

Sal can make another video on the topic by this method or you can provide the link in your courses, as you may like. Thank you.