Subtract previous value in same column

[Marico]

Hi there,

Please see attached data sheet. It contains production readings of various brick machines. The readings are continuous (the counters on the machines can’t be reset). What I need is a formula (in Column D) that can subtract the previous reading (value) of the same machine - in order to get the production total for the day (for the specific machine). The best I could do is a formula that can only subtracts the last entered value from the first entered value in the column (as can be seen on the sheet).

Hope someone can help.

Henco

[Glenn Kennedy]

In E10, copied down, use this:

=C10-LOOKUP(10^300,$C$2:$C9/($B$2:$B9=B10))

[tim201110]

D10 =C10-INDEX($C$2:C9,MAX(IF($B$2:$B9=B10,ROW($B$1:B8)))) as array formula and pull dwn

[Marico]

Wow! Thanks Glenn and Russia, both works beautifully. I just realized how much I still have to learn.

Thanks again.

Henco