I did not mean to leave you hanging on that one. I had a weekend come
up out of no where.
There are a lot of ways to do this. I will cover three of them.

If the information is in Column A to reference and Column B to get
Customer name then you can use Vlookup. this is a vertical look up
formula. It finds what you are looking for in one column and then
moves over a number of columns that you specify. So it woudl be
=Vlookup(D4 - Assuming that is where the number is,A3:B24 - Assuming
this is your array of data, 2 since it is in the "B" column, True
Finds closet match False finds exact match)

=LOOKUP(D4,A3:A24,B3:B24) Same principal but you just specify what to
lookup, where to find it, and what column to chose result.

and last but not least is SUMPRODUCT((A3:A24=D4)*(B3:B24)) You can
add as many conditions as you want and it works when workbooks are
closed.

Jay