is there a fast way to tell all the numbers that a spesific number divides on without leftovers (like for the spesific number "20" it divedes on 1,2,4,5,10,20 and stays as an integer) ? How to find those "1,2,4,5,10,20" in the fastest way ?

that's my code :

#!/usr/bin/perl
use Math::BigInt;

print "Enter the big number : ";
$x = readline(*STDIN);
print "Enter the little number : ";
$y = readline(*STDIN);
$z = $x - $y;
$i = $z;
@all = '';
$j = 0;
system cls;

($sec,$min,$hour,$mday,$mon,$year,$wday,$yday) = gmtime(time);

while ($i ne 0) {
$t = $z / $i;
$k = Math::BigInt->new($t);
$k = $k->is_int();
if ($k eq "1") {$j++; $all[$j] = "$t\n";}
$i--; print "$i\n";
}
($sec1,$min1,$hour1,$mday,$mon,$year,$wday,$yday) = gmtime(time);

$data="Dis.txt";
open(DAT, $data) || die("Could not open file!");
@al=<DAT>;
@al = @all;
open(DAT,">$data") || die("Cannot Open File");
print DAT @al; 
close(DAT);

print "@all It took ", $min1 - $min, " minuts!\n";
$w = readline(*STDIN);
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now how to make it find those numbers FASTER ?

20040705 Edit by castaway: Changed title from 'Didision'