use Math::BigFloat lib => 'GMP';

##</code><code>##

use Math::BigInt;

  # or make it faster with huge numbers: install (optional)
  # Math::BigInt::GMP and always use (it will fall back to
  # pure Perl if the GMP library is not installed):
  # (See also the L<MATH LIBRARY> section!)

  # will warn if Math::BigInt::GMP cannot be found
  use Math::BigInt lib => 'GMP';