Question

7^4k ≡ ______ (mod 100) 

(1) 1 

(2) 2 

(3) 3 

(4) 4

Answer 1

(1) 1

7^4k ≡______ (mod 100) 

y^4k ≡ y^{4 x 1} = 1 (mod 100)