meter useage problem

From: ipsenfixer (ipsenfixer_at_discussions.microsoft.com)
Date: 08/30/04 

Date: Mon, 30 Aug 2004 09:59:12 -0700

Hi all.
I have a natty problem, in a table i have date, and meter reading fields, i
want to add a field inwhich the usege is displayed ie todays reading is
subtracted from yesterdays reading and the result displayed in a used field.
Can anyone help 

-- 
ipsenfixer