Let's say I have 2 columns of data on worksheet "Data" - column A is date,
and column B contains numeric values. Using a date found on worksheet "Test"
(in the same workbook), I'd like to lookup that date on "Data" and calculate
the average of the last 100 days of the values in column B.

It's easy enough to get the last of the 100 days using a simple VLOOKUP, but
I thought I might return the row of that cell found in the VLOOKUP and use
that value to construct an AVERAGE. Something like

AVERAGE(R[x-100]C[2]:R[x]C[2])

where x is the row that was found with the VLOOKUP. Does anyone know how to
return the row that results from a VLOOKUP? Or better yet, is there an
easier way to accomplish this task?

Thanks in advance!
Tom