I'm not sure to understand your issue.
The "<varies>" appears when you have several instances of the same object type and the instances have different values for their instance variable.
You can't put the value "<varies>" to a numeric variable, since it is not the correct type (you're trying to put some text where numbers are expected).
By default an instance variable can vary, so that's not something you have to put in.
Perhaps explain in a clearer way what you're trying to do, and possibly post a capx of where you're at to makes things easier to understand.