use Math::BigInt;
my $n = 2;
my $k = 0;
my $x = Math::BigInt->new($n);
my $z = $x->bnok($k);
printf("$n choose $k = %d\n", $z);
printf("$n choose $k = %d\n", $z->as_int());
printf("$n choose $k = %s\n", $z->bstr());
printf("$n choose $k = %d\n", $z->numify());