<?php $num = 15623; $part_length = 1476; $parts = $num / $part_length; for ($i = 0; $i < $parts; $i++) { $start = $i*$part_length; $end = $start + $part_length; $ranges[] = [$start+1, $end]; } if ($num % $part_length) $ranges[count($ranges)-1][1] = $num; foreach ($ranges as $range) { echo "${range[0]}:${range[1]}\n"; }