Question

(1+2+3+......+100)+(-1-2-3-.....-103)= ?

Answer 1

[1+2+3+...+100]+[-1-2-3-...-103]
⇒[100·101/2]+[-103·104/2]
⇒[50·101]+[-103·52]
⇒5050+[-5356]
⇒-[5356-5050]
⇒-306;

Answer 2

(1+100)*100/2  +  (-1-103)*103/2=

=101*50  + (-104)* 103/2=

=5050 -52*103=

=5050-5356=

= -306