Question

1+2+3+4+.....+199=??

Answer 1

Se aplica formula lui Gauss
$1+2+3+...+199=\frac{199\times 200}{2}=19900$

Answer 2

Suma lui Gauss: n*(n+1) / 2

(199x200) / 2 = 199 x100 = 19.900