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Determinati ultima cifra nenula a produsului
P= 5 LA puterea 48 x 2 LA puterea 45 x cu 3 la puterea 17
Determinati ultima cifra a sumei
S = 5 LA puterea 129 + 7 LA puterea 28
Va rogggggg


Răspuns :

U(5^48) = 5^4k+1=5^4k*12+0=5^4=.....5 U(2^45)=2^4k+1=2^4k*11+1= 2^1 = 2 U(3^17)=3^4k+1=3^k*4+1=3^1=3 P = 5*2*3=10*3=30, U(p)=0 U(5^129)=5^4k+1=5^4k*32+1=5^1=5 U(7^28)=7^4k+1=7^4k*7+0=7^4=......6 U(S)= 5+6 = 11,deck ultima cifra este 1