In this video, we introduce the concept of modular arithmetic.

  1. Congruence modulo n - Let a,bZ. Then abmodn if n divides ba or in other words a+nk=b for some integer k.

  2. Congruence modulo n lets us take an equation and reduce modulo n. For example, the equation 1+52+53=151 becomes 1+52+53151mod3.