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Questions - discrete-mathematics

How to handle "((9^x)-2)%5" without overflow at higher x?

I'm doing some exam prep for my discrete mathematics course, and I have to implement the function f(x) = ((9^x)-2)%5 Since the values of our x in the assignment is 100000 < x <= 1000000, I'm hav...
test-img

Thybo

c

discrete-mathematics

integer-overflow

Votes: 0

Answers: 1

Latest Answer

Since you are calculating modulo 5, multiplications can be done modulo 5 as well. 9 is congruent to -1 modulo 5. Thus 9^x is congruent to (-1)^x modulo 5, i.e. 1 if x is even and -1 if x is odd. Subtr...
test-img

nielsen

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