Is there a SUM formula that can automatically resize as you copy and paste
it, such that ,it will sum all the previous rows up to the previous SUM
formula?

What I want to do is very similar to a subtotal, but without any common item
to subtotal by.

EXAMPLE:
1] 7
2] 5
3] 6
4] <SUM formula here for rows 1-3 RESULT 18
5] 2
6] 8
7] <copy above formula from 4, but have SUM rows 5-6 RESULT 10
8] 3
9] <copy above formula from 4, but have SUM row 8 RESULT 3

Thanks