Howdy,

I was able to reproduce the original problem on my system and, after
making the change suggested by Tels, found that the commands produced
the following output:

 $ perl -MMath::BigInt=lib,GMP -e 'my $b = 0xc0010203; my $m = Math::BigInt-> new (2) ** 24 -
 1; warn $m + $b'
 3238068738 at -e line 1.
 $ perl -MMath::BigInt=lib,GMP -e 'my $b = 0xc0010203; my $m = Math::BigInt-> new (2) ** 32 -
 1; warn $m + $b'
 7516258818 at -e line 1.

These match the results produced by bc.

Here's the output requested by Bram:

 $ perl -MMath::BigInt=lib,GMP -Mbignum=version
 bignum			 v0.23
 Math::BigInt		 v1.89 lib =>  Math::BigInt::GMP v1.24
 Math::BigFloat		 v1.60

The output requested by Tels was the same.

-- 
Matt                                                 http://ftbfs.org/