we use the sum of an arithmetic formula
1 -2 -3 - 4 -5 ....-96 - 97 - 98 - 99 = 1 + Sn
\(S_{n} = \frac{ a_{1} + a_{n} }{2} * n\)
n = 98 (-2, -3,......98, -99)
a₁ = -2
a₉₈ = -99
\(S_{98} = \frac{-2 + (-99)}{2} * 98 = \frac{-101}{2} * 98 = -50,5 *98 = 4949 \\ \\ 1 - 4949 = -4948\)
Answer - 4948
