I have a somewhat complicated sumproduct I'm trying to calculate. First, I
have a table that contains number of units by month, and a cost per unit for
each line of entry (A3:G8 below). So one task is to multiply the number of
units x the cost per unit by each Tower for each month -- this is a simple
sumproduct formula.

But in addition to this multiplication, I also have to multiply each of the
Tower entries (units x cost) by an (escalation) factor (in A11:G13 below).

So for instance, in Month 1 (column C), I need to calculate the sumproduct
of all the number of units x the $ per unit x the escalation factor relevant
to each of the towers. Note that I need to do this by month, not for the
whole table at once. But I do need one formula to for each month.

Any suggestions? Thanks a lot in advance.

A B C D E F G
1 $ <----- Months -----
2 /unit Number of units
3 Tower1 100 1 1 1 2 3
4 Tower2 120 5 3 3 3 2
5 Tower2 105 3 4 7 10 10
6 Tower1 130 2 2 5 6 8
7 Tower3 100 8 10 12 15 15
8 Tower3 110 6 6 5 4 3
9
10 Escalation factors
11 Tower1 1.1 1.2 1.3 1.4 1.5
12 Tower2 1.0 1.0 1.0 1.0 1.0
13 Tower3 1.2 1.2 1.2 1.3 1.3
14
15 Total: ? ? ? ? ?