because your code is equivalent to 
my ($in_out) = @_;
my ($out,$diver,$grade) = split(/,/, $in_out, 3);
my $float = ($out)**(1/$grade)*$diver;
my $in = Math::BigInt->new($float);

[download]
so you are making the calculation with floats and then converting the result to a bigint.

You have to convert first the numbers to bigints and then make the math!!!

In reply to Re: Misunderstanding with Math::BigInt by salva
in thread Misunderstanding with Math::BigInt by Smoke

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