A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Another approach would be to use 0000 - 9999 and have 0 denote NOT WEIGHED - use the custom number format
0000;0000;"NOT WEIGHED"
and 0 will display as - but not be entered as - "NOT WEIGHED" so any formulas that you use would need to account for 0 meaning that instead of the numeric value 0.