Question

calculeaza;2015-1-2-3-...................-49=?

Answer 1

2015- 1-2-3-4- ... - 49 = 2015 - (1+2+3+...+49).
$1+2+3+...+49= \frac{49*50}{2} = \frac{2450}{2} =1225.$
2015 - 1225 = 790.