Mr. Low,

Yes - when this formula is entered in E2 and copied downward, it
subtracts the previous subtotals, leaving only the current one.
=IF(A2=A3, "", SUMIF($A$2:A2, A2, $C$2:C2) - SUMIF($A1:$A$2, A2, $E1:E$2))

I'm using Excel 2003, which automatically rearranges the dollar signs as
necessary, so that in row 4 and below the subtracted function looks like
this:
.... - SUMIF($A$2:$A3, ...

- David

Mr. Low wrote:
Dear Sir,

I used the formula =IF(A2=A3, "", SUMIF($A$2:A2, A2, $C$2:C2)) in the table.
Cell D4,D5 and D10 are correct, however D14,D17 and D21 are not correct as
it also add up the figure of the previous block that has the same reference.

Is there anyway to modify this formula ?

Thanks

Low

A B C D
1 Product Invoice Amount subtotal
2 A491 V4148 222.00
3 A491 V4149 1,410.00
4 A491 V4150 282.00 1914 Correct
5 C225 V4151 672.00
6 C225 V4152 1,344.00 2016 Correct
7 H247 V4153 118.00
8 H247 V4154 118.00
9 H247 V4155 427.00
10 H247 V4156 1,332.00 1995 Correct
11 A491 V4157 120.00
12 A491 V4158 222.00
13 A491 V4159 113.00
14 A491 V4160 222.00 2591 Error
15 H247 V4161 118.00
16 H247 V4162 180.00
17 H247 V4163 222.00 2515 Error
18 C225 V4164 444.00
19 C225 V4165 528.00
20 C225 V4166 339.00
21 C225 V4167 1,056.00 4383 Error
22 D208 V4168 528.00
23 D208 V4169 328.00
24 D208 V4170 202.00 1058 correct