There are four cells (merged cell ranges) I want users to
fill data into before leaving the worksheet (worksheet
name is "Scorecard"); G26:I26, AG26:AI26, G44:I44, and
AG44:AI44. I have an Auto_Open sub in place to open the
workbook on this "Scorecard" worksheet. These four cells
are weighting factors and the numbers, formatted percent,
must equal 100%. Also, there must be a number entry in
each of the four cells, even if it is zero. If the user
does not make an entry (blank cell) a message must come up
saying "Weight for cell *** is required." If they leave
multiple cells blank, the message would include those
cells as well. Users cannot leave the worksheet until all
four cells are populated.

What would the code be? Would I put the code in the
worksheet code object, or in Module 1?