<?php
 
function num_short($n, $precision = 1) {
    if ($n < 1000) {
        $n_format = round($n);
    } else if ($n < 1000000) {
        $n_format = round($n / 1000, $precision) . 'K';
    } else if ($n < 1000000000) {
        $n_format = round($n / 1000000, $precision) . 'M';
    } else {
        $n_format = round($n / 1000000000, $precision) . 'B';
    }
    return $n_format;
}
 
echo num_short(5000, 1)."\n"; //outputs 5K
echo num_short(5004, 1)."\n"; //outputs 5K
echo num_short(5040, 1)."\n"; //outputs 5K
echo num_short(5400, 1)."\n"; //outputs 5.4K
echo num_short(5900, 1)."\n"; //outputs 5.9K
echo num_short(5990, 1)."\n"; //outputs 6K
echo num_short(5999, 1)."\n"; //outputs 6K

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