Question

The value of the series `(1+2-3-4+5+6-7-8+9+10-11-12+…-99-100=?`

Answer 1

`(1+2-3-4+5+6-7-8+9+10-11-12+…-99-100`
Grouping taking 4 terms in a group

`=[(1+2-3-4)+(5+6-7-8)+(9+10-11-12)+…....+(97+98-99-100)]`

`=-4-4-4-........"up to.25 terms"`

`=-4xx25=-100`