Using Eulers Theorem find the least nonnegative residue mod
Using Euler\'s Theorem, find the least nonnegative residue mod m ofthe following integer n below.
Solution
a)
29=9 mod 20
So, 29^198=9^198 mod 20
9^2=81=1 mod 20
So,
9^198=(9^2)^99=1^99=1 mod 20
b)
79=81-2=-2 mod 9
So
79^79=(-2)^79
(-2)^3=-8=1 mod 9
(-2)^79=(-2)^78*(-2)=((-2)^3)^26*(-2)=-2 mod 9
So least non negative residue is -2+9=7
