#!/usr/bin/perl -w
use strict;
my( $num, $den )= ( 1, 7, @ARGV )[2&@ARGV,-1];
my $rem= $num % $den;
my %seen;
my $rep= '';
while(  1  ) {
    $rem *= 10;
    last
        if  exists $seen{$rem};
    $seen{$rem}= length( $rep );
    $rep .= int( $rem / $den );
    $rem %= $den;
}
substr( $rep, 0, $seen{$rem} )= '';
print "$num / $den = ...$rep\n";