You also have to make sure you don't accidentally select an already selected
item... if you do, it will be included in the selection twice (or more if
you select it again multiple times)! Here is a demonstration for those not
familiar with this "quirk". Leaving the cells empty, make a multi-cell
selection by Ctrl+Clicking on each cell in the following order...
A1 A5 A10 A5 A20
After you do that, A5 will be included in the selection twice. To see this,
copy/paste and then run this macro...
Sub Test()
Dim Cell As Range
For Each Cell In Selection
Cell = Cell + 2
Next
End Sub
Since the cells are empty when you start, you would expect each cell to now
contain the value 2, but take a look at what is in A5. You can also see the
double inclusion of A5 in the selection by executing this line in the
Immediate Window...
? Selection.Address
However, I think the above macro better demonstrates how erroneous outputs
can possibly occur by iterating the Selection range.