We have a resourcing spreadsheet to track utilization. For each month, I need to assign % FTE based on how long people work on an activity. To increase simplicity, I'd like to use a drop-down list of common times (e.g. 1/2 day, 1 day, 2 days, etc.) and based on the selection, that same cell is populated by the equivalent FTE (e.g. 0.02, 0.05, etc.)

I've toyed with this, but keep getting a 'circular argument' warning. Even after the cell is populated with, say 0.02, I'd like the drop-down list to still exist and allow the user to make a different selection.

I have created my drop-down list using the data validation within excel.