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aflati ultima cifrav a nr c=76^20×67^30+45^21×39^22


Răspuns :

U(76^20)=U(6^20)=intotdeauna 6
U(67^30)=U(7^30)=U(7^4k+2)=U(7^2)=9
U(45^21)=U(5^21)=intotdeauna 5
U(39^22)=U(9^22)=U(9^2k)=1
=>ultima cifra e 1
cu U( ) am notat ultima cifra