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());

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I'm guessing I'm doing something wrong because this just prints 2 choose 0 = 3. I'm pretty sure it should be 1. 
my $n = 5;
my $k = 2;
my $x = Math::BigInt->new($n);
my $z = $x->bnok($k);
printf("$n choose $k = %d\n", $z);

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The above correctly prints 5 choose 2 = 10. So, what am I doing wrong? Or is bnok() broken?? BTW..I tried BigFloat too...with same result. 
***

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THANKS to everyone that responded. I was indeed using an older verion (1.89_01). I use Ubuntu and I guess Math::BigInt comes as part of some other package. When I installed it directly via 'apt-get install libmath-bigint-perl' I now get version (1.993) which does indeed get the 2 choose 0 correct. 
***

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Thanks again for the responses!

In reply to BigInt bug? by shao.lo

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