Question

5+10+15+20+.... + 1000 rezolvare suma gaoss

Answer 1

5 + 10 + 15 + 20 + ... + 1000 =

= 5 · (1 + 2 + 3 + 4 + ... + 200) =

= 5 · $\frac{200*(200+1)}{2}$ =

= 5 · $\frac{200*201}{2}$ =

= 5 · 100 · 201 = 100500.

/rfd