Question

Determinati ultima cifra a numarului:
x=2⁰+2¹+2²+2³+...+2¹⁹⁹⁹+2²⁰⁰⁰

Answer 1

[tex]x=2^0+2^1+2^2+...+2^{2000} \\ -2x=-2-2^2-2^3-....-2^{2001}\\ .........................................\\ -x=1-2^{2001}\\ x=2^{2001}-1\\ Acum\ trebuie\ sa\ faci\ ciclul\ puterilor\ lui\ 2.[/tex]