----- Original Message ----- From: "David Cleaver" <wraithx at morpheus.net> > However, if anyone knows of a faster way to do this conversion, I'd still > like to hear about it. IIUC, I'd be left-shifting the first number 64 places (using mpz_mul_2exp), and adding that to the second number (mpz_add). I haven't done any timings, however. Cheers, Rob