formula needed

[ericlch16]

I have these 2 column with headers [number], [sum]

[number] [sum]
1 1
1 -2
2 4
2 3
3 4
4 5
4 6

I want a third column [net]so that it subtotal based on column A [number] i.e

[number] [sum] [net]
1 1 -1
1 -2 -1
2 4 7
2 3 7
3 4 4
4 5 11
4 6 11

which formula i need to put in C so that i get these?

if column is not sorted, is it possible to have a generic formula even though Column A is not sorted?

thanks

 

[jasonb75]

Adjust ranges to suit

=SUMIF($A$2:$A$8,A2,$B$2:$B$8)