I have a spreadsheet with customer's account numbers in column A and other
data associated with the account number through column Z.

I'm looking for a way to use the fill color (gray) for the entire row if the
account numbers match, then for the next match use fill color (white) and so
on.

A
1 12345 gray
2 12345 gray
3 12345 gray
4 67891 white
5 67891 white
6 57842 gray
7 54123 white
8 54123 white

Thanks in advance for the help.