Sumproduct in Numbers driving me mad!

Question

Hi All, looking for someone to tell me im being really silly here, this is driving me mad!!!
So, I've been trying to impliment the following sumproduct in Numbers, here are my two tables, both on the same sheet. This is a test workbook ive been playing around with...
Table 1
A
B
C
D
1
Make
Month
Sold
Price
2
Ford
June
1
£100.00
3
Ford
June
3
£200.00
4
Ford
May
4
£300.00
Table 2
A
B
C
1
Make
Month
Total
2
Ford
June
? = the following formula: =SUMPRODUCT((Table 1::A2:A4=A2)×(Table 1::B2:B4=B2)×(Table 1::C2:C4))
Numbers comes to the value of 1. Interestingly enough, when i export to Excel, the answer magically becomes 4. Im a bit of an Excel geek so would like to think i know my stuff, but am trying to switch to Numbers for simple stuff because I like being able to view sheets on my iPhone, but this is driving me mad!
Any advice you can give would be brilliant!
Thanks in advanced,
Dave.

Answer 1

I would add a new column to the top table (in my example I am calling it "Sales Data"):
The new column is called "Extended Amount" and is the product of the number sold and the price
E2=C2×D2
this is shorthand for select cell E2, then type ( or copy and paste from  here) the formula:
=C2×D2
select E2 and fill down
Now in the the summary table (the lower table):
C2=SUMIF(Sales Data::B, B2,Sales Data::E)
this sums the extended amount for all months that match what you enter in cell B2 in the month column of the table "Sales Data"