I have a table with the months in row 6. Revenue is in row 9 and costs are
in rows 10 through 38. Cell c6 is 1 for January and cell c9 is January
revenue. My formula to lookup the current month (stored in cell o3) is
=HLOOKUP$O$3,$C$6:$M$38,4,FALSE)

This works fine and returns the value in k9. But I would also like a to get
the year to date revenue by adding everything from c9 to k9.