PHP function to convert a given number to a shorthand version. Ex: convert $1,000,000 to $1M

convert-num-to-abbrev.php

<?php
if ( ! function_exists( 'PREFIX_abbreviate_num' ) ) {
    /**
     * Converts the given number to an abbreviated version of it and returns that value.
     *
     * Ex: PREFIX_abbreviate_num( 100000 ) would output 100K.
     *
     * @since 1.0.0
     *
     * @param $num int
     * @return string
     */
    function PREFIX_abbreviate_num( $num ) {
        $units = ['', 'K', 'M', 'B', 'T'];
        for ($i = 0; $num >= 1000; $i++) {
            $num /= 1000;
        }
        return round($num, 1) . $units[$i];
    }
}