Hi John

if I understood you correctly this seems to be the same as my
assumption. E.g.
A2: Product
B2: month 1 units
C2: month 2 units
....
M2: month 12 units

If this is your spreadsheet layout, you can use my formula. If you have
a differing layout you can 8if you like) send me your spreadsheet and
I'll adapt the formula for you

HTH
Frank


John wrote:
Frank,
I should have mentioned, the list is rows structured like this:
product, month1 units, month2 units, month3 units...month12 units,
initial 3mo units.

I need to help with a formula to calc the "initial 3mo units." (I'm
actually simplifying the data list for the purpose of discussion.)


"Frank Kabel" wrote in message
...
Hi John,
Some assumptions: Your products are listes in column A and your
month
are listed in row 1. So the activitie for the first product in the
first month would be listed in cell B2. then try the following
formula for the first product in row 2:
=SUM(OFFSET(B2,0,MATCH(TRUE,B2:M20,0)-1,1,3))
enter this as array formula (CTRL+SHIFT+ENTER)

HTH
Frank