I'm trying to implement an e-voting algorithm, which is described at the paper "Internet Voting Protocol Based on Improved Implicit Security" by Abhishek Parakh & Subhash Kak.
At the Example 1 described in the paper where we have m1=85, at the step 2 it says
"2. Choose randomly and uniformly a number r1 = 101 and compute r2 = m1*(r1)^-1 = 85*(101)^-1=85*28=67mod257"
How is this possible? I mean how can 101^-1 be 28?