jmc

The sign function $\text{sgn}(x)$ is defined by $$\text{sgn}(x)=\{\begin{array}{rl}-1& \text{if }x<0\\ 0& \text{if }x=0\\ 1& \text{if }x>0.\end{array}$$Compute ${\sum }_{n=-10}^{20}\text{sgn}(n).$