Question

1+2+3+4+...+66 = ??? ajutati-ma va rooooggggg

Answer 1

$1+2+3+..+n= \frac{n(n+1)}{2}$  (Suma lui Gauss)

$1+2+3+4+...+66= \frac{66(66+1)}{2} =2.144$