#! /usr/bin/perl
my ($n, $m) = @ARGV;
my $ans = fact($n)/fact($m)/fact($n-$m);
my $err = $ans - sprintf("%.0f", $ans);
print "$n choose $m: $ans (error $err)\n";

sub fact {
  my $fact = 1;
  $fact *= $_ for 1..$_[0];
  $fact;
}