very small numbers, like those in our examples). 2 6 means "2 multiplied by itself 6 times", or 2*2*2*2*2*2, which is 64 'mod' means " modulo ", which is "remainder after integer division", so "64 mod 13 = 12" (64/13=4 with 12 "left over") it's very much like the "wrapping" we