a) 290 mod 26
We subtract the largest multiple of 26 which is less than 290. The answer we get after the subtraction is the answer.
Largest multiple of 26 is 286, because 26 * 11 = 286
290 - 286 = 4.
290 mod 26 = 4.
b). 9^(-1) mod 26 = 0.111 mod 26.
0 * 26 = 0.
The largest multiple of 26 which is less than 0.111 is 0.
We subtract this from 0.111
0.111 - 0 = 0.111
9^(-1) mod 26 = 9^(-1) = 0.111
c). -15 mod 26.
Take note this is negative numbers. But same rules applies here.
The largest multiple of 26 which is less than -15 is -26.
We subtract this from -15
-15 - (-26) = -15 + 26 = 11
-15 mod 26 = 11
