Using Fill Color to change Percentages

[bem_388]

I am trying to figure out how to change the percentage of completed tasks by changing the fill color from white to an alternate color in one cell.

If I have 20 tasks and I use the basic formula to track percentages, I have to manually change the math each time a task is completed.

I would like to change the color of the cell (ie: from white to red) and have the change in color automatically perform the math to change the overall percentage.

 

[shg]

Why not instead enter something in a column to indicate that the task is complete, and then use that to both for changing the cell color (via conditional formatting), and in the formula that computes percent complete?