Thanks for the suggestions. I may be able to use JMB's Sub test2 as a
starting point and see if I can work with it, but let me give you some
more info. I think I simplified too much for the sake of the example.

What I'm really doing is copying the values of each of the cells in my
ranges into cells within an excel model that takes a number of other
assumptions and the output is several return metrics that I'm trying to
put into the grid. I'm not actually calculating anything within the
macro.

So each cell of my ranges represent an assumption that changes with
different criteria ("buckets" for loan size, FICO score and CLTV).

So for each combination of loan size/FICO/CLTV, I'm changing my
assumptions for interest rate, avg line size, loan expenses, loss
rates, etc... (I have a 20x5 range for each of these assumptions).
These assumptions, along with many other things, are fed into my model.

So in words, what I'm doing is:

Copy the upper-leftmost cell value in range (A, B, C....n) and paste
into the correct assumption cell in the model (identified
individually). Then copy the output cell and paste the value into the
upper-leftmost cell in range O.

Then do the same with the next cell in each range (top row, 2nd column)
and so on, through the bottom-rightmost cell.

Sheesh. I don't know why I'm having such a hard time explaining this.
Sorry for being so ineloquent!