I can do this with formulae only.
[video]https://app.box.com/s/qnvltpugnh7ljp74xy2imidvxen9th3a[/video]
Trying to add an animated gif… please be patient!
OK, can't. Grrrr.
Click on the link above it should take you to a gif.
If you like it, paste those pesky cross-post links somewhere in this thread and I'll attach the workbook.