(91 + 92 + 93 + . . . . . . + 110) is equal to

Answer: Option B

$$\begin{array}{rl}& 1+2+3+......+n=\frac{n\left(n+1\right)}{2}\\ & \therefore 91+92+......+110\\ & =\left(1+2+......+110\right)-\left(1+2+......+90\right)\\ & =\frac{110\times 111}{2}-\frac{90\times 91}{2}\\ & =6105-4095\\ & =2010\end{array}$$