What makes you think it's a problem returning a big num from the subroutine? There's no evidence of that. Problem: use bignum; isn't in effect in the eval. Fix: 

sub operation {
    my ($arg) = @_;
    my $product = eval "use bignum; $arg";
    return  abs $big_number - $product;
}

[download]

Or use the existing bignum instead of making a new one. 

sub operation {
    my ($arg) = @_;
    my $product = eval "\$arg";
    return  abs $big_number - $product;
}

[download]

In reply to Re: bignum, can't return outside a subroutine by ikegami
in thread bignum, can't return outside a subroutine by zli034

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