PHP Manual: Get modulus of an arbitrary precision number

string bcmod(string $num1, string $num2, intnull $scale = null)

Get the remainder of dividing num1 by num2. Unless num2 is zero, the result has the same sign as num1.

Returns the modulus as a string, or null if num2 is 0.

Version	Description
8.0.0	`scale` is now nullable.
7.2.0	`num1` and `num2` are no longer truncated to integer, so now the behavior of bcmod follows fmod rather than the `%` operator.
7.2.0	The `scale` parameter was added.

Example #1 bcmod example

<?php
bcscale(0);
echo bcmod( '5',  '3'); //  2
echo bcmod( '5', '-3'); //  2
echo bcmod('-5',  '3'); // -2
echo bcmod('-5', '-3'); // -2
?>

Example #2 bcmod with decimals

<?php
bcscale(1);
echo bcmod('5.7', '1.3'); // 0.5 as of PHP 7.2.0; 0 previously
?>

bcmod