Răspuns:
2^2017
ultima cifra (2^2017)
U =ultima cifra
U(2^1)=2 1
U(2^2)=4 2
U(2^3)=8 3
U(2^4)=6 4
U(2^5)=2
2017:4=504rest 1
U(2^ 2017)=U(2^1(1de la rest))=2