Assuming your table 1 from A2:B7 and table 2 from D2:E7 and both tables are
sorting in ascending order

Formula in F1 =SUMPRODUCT(B2:B7,E2:E7)

"Steven Cheng" wrote:

I have two tables, both with two columns.

the first column in each table is a key index number. I want to be able to
multiple the values in the second column off when each record has the same
key value and then and return the summed value for the whole population.

eg.

Table 1

Index Rate
1 .03
2 .04
3 .03
4 .04
5 .02
6 .03

Table 2
2 1000
4 1500
5 2000
6 3000
1 2500
3 2750

the sumproduct/sum(if....) should return (2500 x .03) + (1000 x .04) + (2750
x .03) + (1500 x .04) + (2000 x .02) + (3000 x .03) = 306.50.