Question

Va rog mult sa ma ajuta-ti ! ( Suma lui Gauss )
S= 5+10+15+...+555

Answer 1

(5+555)*554:2=aici calculeaza tu. 

Answer 2

$\displaystyle 5+10+15+...+555=5(1+2+3+...+111)= \\ \\ =5 \times \frac{111(111+1)}{2} =5 \times \frac{111 \times 112}{2} =5 \times \frac{12432}{2} =5 \times 6216=31080$