Fill Series if adjacent cell value is greater than zero

Hi,

I want to give a location (Column A) a number in Column B based on whether or not it contains a particular item. The quantities of these items are contained in Columns C and D. The number will be sequential but will be only assigned if Columns C or D or both contain a value greater than 0.

There will be blank cells due to the fact that C an D may both be zero but as it continues down column B the number should be the next in sequence. I have tried to filter C and D but fill series doesn't work on the resultant filtered cells in B. Is there a formula I can put in B1 to give me this sequential numbering with skipped or blank cells.

I have attached an example that I hope explains what I am trying to do.
Thanks
Max

maxflower,

Welcome to the forum!
Attached is a modified version of your example workbook. In cell B2 and copied down is this formula:
=IF(OR(C2>0,D2>0),COUNTIF($B$1:B1,">0")+1,"")