just keep on getting a smaller remainder.
19^92 mod 92
19^2=361 mod 92 =-7
so 19^92 = -7^46
-7^3=343 mod 92 = -25
=> -25^15 *-7
-25^2=625 mod 92 = 19
=> 19^7*25*7
19^2 mod 92 = -7
-7^3 mod 92 = -25
=>-25*19*25*7
=>-19*19*7
=> -7*-7
this gives 19^92 mod 92 = 49