After sizing your geographical market, ask yourself what you want your market share to be in five years.
Then follow the steps for goal seek (under Tools) within the spreadsheet. The model will calculate the required monthly net revenue over the five year planning horizon in just second.
Divide the monthly net revenues by the sales quotas you've set for your sales representatives to determine if you have enough productive staff to drive your net revenue goals. If so, great! If not, hire additional sales representatives.