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Modulo

x = 3^(-3) mod 250
= 3^(97) mod 250

I would like to do it the first way, but I dont know how?

The second way I can do, but its 97, so its longer. I cant remember how to do it the first way, can someone remind me? Thanks
Reply 1
Avatar for DFranklin
DFranklin
18
I'm not sure there's a general "easier" way of doing it, but since 3 is quite small, it's easy to find k s.t. 3k = 1 mod 250. Then k = 3^(-1) and you just need to find k^3.
Now that DFranklin has shown you how to do part 1, you can exploit this is working out part 2.

Hint: Look at the indices.
Reply 3
Avatar for 2710
2710
OP
18
Original post by DFranklin
I'm not sure there's a general "easier" way of doing it, but since 3 is quite small, it's easy to find k s.t. 3k = 1 mod 250. Then k = 3^(-1) and you just need to find k^3.


nice thanks!

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