Question

b) Aflaţi ultima cifră a sumei S= 1+ 2^2+ 3^3 + 4^4 + ... +10^10 .

Answer 1

Răspuns:

1

Explicație pas cu pas:

U(1+4+7+6+5+3+6+9+0)= U(41)=1

Answer 2

$\it u=u(1+4+7+6+5+6+3+6+9+0) =7$

$\it u(9^9)=u(9^8\cdot9)=u[(9^2)^4]\cdot9=1\cdot9=9\\ \\ u(8^8)=u(8^4)^2=1\\ \\ u(7^7)=u(7^4)\cdotu(7^3)=1\cdot3=3$