Carol, here's a solution ...
Hit the KEY button and go to the Pass-In Fields tab.
Define a variable. You have the choice of defining the type as Text / Whole Number / Decimal Number.
In this example, let's assume I have defined a variable called "Customer" as type Whole Number.
You can use an SSI Script function called SetValue to assist.
If it is just a simple set the "Customer" variable to a "1" you would pop this script into the footer of one of your questions. Be careful that the question is not being skipped if you want all surveys to have the "Customer" variable updated correctly.
If you need a conditional type example where Customer=1 if Q1>99, otherwise Customer=2, check this out ...
[%Begin Unverified Perl