running total calculation

[PAULCALLAGHAN]

I'm using Access 2000 and would like to create a formula that gives the running sum of invoice amount within a customer. I want to then use this calculation in another formula.

Can someone please help me to construct this running sum calculation?

I'd like to do it in a query so I can the results of that query in another query. However, I'm open to suggestions for a different strategy.

 

[hneal98]

is this for a query, form, report?

 

[PAULCALLAGHAN]

I would like to use this in a query, because I plan to use this calculation in a separate query. However, I am open to another strategy.