Thread: SUMIF function

I have the following problem that I would like to approximate in this simplified manner - Imagine you have these two columns:

A 1
A 2
A 3
B 0
B 2
A 4
A 5
B 4
B 8

and you want to generate one third column out of these two that adds up all previous values of A and B so far at each step whenever A and B appear again. In other words the new, third column should look like this:

0
1
3
0
0
6
10
2
6

10 for example comes from the sum of all 'A' letter values before the new one (1+2+3+4). By analogy 2 comes from the sum of all 'B' letter values before the new one (0+2). I hope it is clear. As you probably understood if the problem was adding all the values of A or B in the end this would be solved easily. But my wish is to have this done in one column in such a way that the current total is shown after each new cell. The constraints are simple - I need to do this all in one column; and I should also not sort the A's or the B's - in other words you cannot change the order. If someone can help me construct this third column out of this data with a function I will highly appreciate it and I thank him/her very much in advance.

If those represent the values in A1 through B9, put this formula in C2 and copy down:

=SUMIF($A$1:A1, A2, $B$1:B1)

You'll have to just expect C1 = 0 since there are no prior values.

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