Basic Multiplication Error

[filmpedler]

Hello, I am trying to just multiply Roll Ft Size x Lin Ft. But I keep getting an error. What am I doing wrong here?

Thank you for any help here.

[TheTimeSavingCo]

One of the things you're multiplying by isn't a number I think

Try adding a zero to each piece of data to force it to be a number before the multiplication:

({Roll Ft Size} + 0) * ({Lin Ft} + 0)