Hi, trueimage. You ask this in the programming forum, so I guess you're looking for a VBA solution. It seems to me you want to write a Worksheet_Change subroutine, one that already knows what range you want to check. Every time you change something on the worksheet that program will run, automatically (because it's named "Worksheet_Change" and because you will have placed it in the code module for that worksheet—I'll show you how, if you don't know already). You'll write the program to look through that range and add up the count of yellow cells, then put that count into the proper place.

How much of that do you already know how to do, and how much of it do you need help with?