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