What us the easiest way to find the solution to 1+2-3+4+5-6+7+8-9+...+208+209-210 ?
+14913 What us the easiest way to find the solution to 1+2-3+4+5-6+7+8-9+...+208+209-210 ?
Hello Guest!
The easiest way to do this is with the Gaussian empirical formula.
\(\sum\limits_{k=1}^{n} k =\dfrac{n(n+1)}{2}\)
\(\sum\limits_{k=1}^{209} k-210 ={\color{black}\dfrac{209(209+1)}{2}-210=}21735\)
!
