I'm using a combo box to select a machine number from tblMachines. After the user selects the machine number, I want to pull up a field in another table to use for a calculation later. Here's the hard part (for me): Each machine has a different amount of changeovers and each changeover is a different amount of seconds. I need to take those amount of seconds to do a calculation. After the user selects the machine number, they then select the amount of each changeover. For example, Machine A-14 has 3 changeovers. CO1 is 296; CO2 is 353; and CO3 is 1000. The user selects A-14 in the combo box, then enters how many of each changeover(ie 3 CO1's, 0 CO2's, and 4 CO3's). I then have to take (3*CO1)+(0*CO2)+(4*CO3). I have different tables for each machine's changeovers (ie tblA6Changeovers, tblA14Changeovers, ect.) Each machine is different and has different elements in each of the changeovers, as well as different amounts of changeovers. How do I do this? Could someone please help me??