The remainder operation

The four operations you’ve seen so far are easy to understand because you’ve been doing them for most of your life. Swift also has more complex operations you can use, all of them standard mathematical operations, just less common ones. Let’s turn to them now.

The first of these is the remainder operation, also called the modulo operation. In division, the denominator goes into the numerator a whole number of times, plus a remainder. This remainder is exactly what the remainder operation gives. For example, 10 modulo 3 equals 1, because 3 goes into 10 three times, with a

remainder of 1.

In Swift, the remainder operator is the % symbol, and you use it like so:

28 % 10

In this case, the result equals 8, because 10 goes into 28 twice with a remainder of 8.