Question

Calculati:
2+3+4+..........+100-1-2-.............-99

Answer 1

2+3+4+..........+100-1-2-.............-99=
(2+3+4+...+100) - (1+2+3+4+ ...+ 99)=
(100·101:2- 1) -(99·100:2)=
(50·101- 1) - (99·50)=
(5 050-   1) - 4 950=
5 049- 4 950=
     99