Example Spreadhseet

1 2 3 4

12 42 45 3
12 78 78 0
12 1234 2345 1111
13 3 5 2
14 1 6 5
14 2 2 4


Here is a sample of my sheet; in column 1 are policy lists sorted
numerically. In column 2 there are a lists of actual prices, and column 3
contains standar prices. Column 4 contains the difference between column 2
and 3. As you can see from column 1 there are several policies that have
duplicates.

I'm looking for a way to group the duplicates in column 1 to get the sum of
the differences in column 4?

--
Kevin