Question

Aflati ultima cifra a nr: a)2^53 b)5^42 c) 7^39 d) 9^81 e)1923^2017

Answer 1

a) U(2^53) = U(2^4×13+1) =U(2^1) = 2

b) U(5^42) = 5

c) U(7^39) =U(7^4×9+3) =U(7^3)=U(342)=3

d) U(9^81) = 9
9 la putere para are intotdeauna ultima cifra 1
9 la putere impara are intotdeauna ultima cifra 9

e) U(1923^2017) = U(3^4×504+1) =U(3^1)=3