# Modular multiplicative inverse problem.

I am trying to calculate the multiplicative inverse of big integers of 256 bits and I am not able to find a good calculator to resolve it.

I have found some online calculators but the result is not correct.

• The calculator GP/PARI can do it very easily. Example Mod(110528812453801822904317758417383912041757712635384174764936784734826169201757, 123897535483928329103220953959296061402998883592235403522219614888467048714837)^(-1). – Jeppe Stig Nielsen Jul 11 '17 at 20:22