Cool application of the binomial. This 'last digits' question happens also
many time in high-school International Mathematical Olympiad, in the
algebric questions.
In Base 10 it's all easy. The hardest would be to ask the last digits in
octal, binary or hexadecimal base. (!)
Great.. Watched all the videos.. Have always wanted to learn shortcuts of
maths. One of my minor goals is achieved at an age of 29 :-D .. At least I
can teach my son/daughter :-) good work.. Thanks a lot