Sequential counting in a separate column based on values in other columns

[JimtheRookie]

Hi, I need help with a query that sequentially counts the number of like items in a database. The screen shot below describes what I need. I need the formula that creates the value in the "Item Number" column. This formula would have to reference the row prior to determine the value it placed in the "Item Number" column. I only know enough to Access to get into trouble. Thanks!

[June7]

Google: Access query row number rank by group

Here is one http://bytes.com/topic/access/answer...ws-based-group

Will need a unique ID field in table.

Alternative is to create report and set RunningSum property of textbox along with Grouping & Sorting features.