# #53 – Modulus

The modulus operator %, used as a binary operator

a % b

is defined as the remainder of a (dividend) divided by b (divisor).  Also known as “modulo“.

The idea is to determine the maximum integer that you can multiply b by to get a result <=a. Let’s call this integer n.  Then the remainder is just a – (b * n).

Examples:

``` int n1 = 5 % 2;    // 1  [5-(2*2)]
int n2 = 39 % 5;   // 4  [39-(5*7)]
int n3 = 10 % 2;   // 0  [10-(2*5)]
```

If a is equal to b, the remainder is always 0.

If a is less than b, the remainder is always equal to a.

If either a or b is negative, the result always matches the sign of a.

``` int n5 = -5 % 2;   // -1
int n6 = 5 % -2;   //  1
int n7 = -5 % -2;  // -1
```

C# also supports the use of the modulus operator for floating point numbers:

``` double d1 = 42.5 % 12.2;  // ~5.9 [42.5-(12.2*3)]
``` About Sean
Software developer in the Twin Cities area, passionate about software development and sailing.

### One Response to #53 – Modulus

1. kai zhou says:

Great summary, thank you Sean.