CALCULATI ultima cifra a numarului n=4*3^10+5*3^14+6*3^18+...+18*3^66+19*3^70
E urgent! Dau coroana primului raspuns si 54 puncte

===============================

U (4*3^10)=U(4*3²)=

U(5*3^14)=U(5*3²)

U(6*3^18)=U(6*3²)

...............................

U(18*3^66)=U (18*3²)

U(19*3^70)=U(19*3²)

deci avem de calculat U (U(4*9)+U(5*9) +U(6*9)+....U(18*9)+U(19*9))=

=U (U(4*9)+U(5*9)+...+U(9*9)+U(0*9)+U(1*9)+U(2*9)+..+U(9*9))=

=U (6+5+4+3+2+1+0+9+8+7+6+5+4+3+2+1)=

U(U(6*7/2) +U(9*10/2) =U(U(21)+U(45))= U(1+5)=6

le-am luat mai babeste la final, ca sa fiu mai sigur

sperca n-am gresit la calcul, tabla inmultiriicu 9 care multiplii apar si de cate ori