I wanted a function to return all factors of an integer, which involves primality testing. Wikipedia search turned up techniques way over my head (not surprising), but their "Naïve methods" gave me this as a start: #include <array.au3> While 1 $n = InputBox("Factorizor", "Input number to factor: ") If @error Then Exit $n = Number($n) $iTimer = TimerInit() $avRET = _Factor($n) $ErrSav = @error $ExtSav = @extended $iTimer = TimerDiff($iTimer) _ArrayDisplay($avRET, "Primes of " &a