Array Formula in A15:
What is named ranges?
Download excel sample file for this tutorial.
Comparing two columns and sum unique values.xls
(Excel 97-2003 Workbook *.xls)
Functions in this article:
Counts the number of cells within a range that meet the given condition
Adds all the numbers in a range of cells
Checks whether a condition is met, and returns one value if TRUE, and another value if FALSE