Congruence Notes for Math 135
... Notation: We could develop the following section formally for an integer made up of an arbitrary
number of digits (using sigma notation), but for simplicity we’ll write, e.g., abcde for the number
whose digits are a, b, c, d, e, i.e. the number 104 · a + 103 · b + 102 · c + 10 · d + e.
Remember that ...