`1+2−3+4−4+5−...+999−999`
`=(1+2)−3+(4−4)+(5−5)+(6−6)+....+(999−999)`
`=3−3+0+0+0+0+...+0`
`=0`
`@Neo`
1 + 2 - 3 + 4 - 4 + 5 - ... + 999 - 999
= 3 - 3 + 4 - 4 + 5 - ... + 999 - 999
= 0 + 0 + ... + 0
= 0
(ko chắc lắm)
`#ava`
`1 + 2 - 3 + 4 - 4 + 5 -....+999 - 999 `
`= 3 - 3 + 4 - 4 + 5 - 5 + .... + 999 - 999`
`= 0 + 0 + 0 + 0 +.... + 0`
`= 0`