Configurator - Component Quantity Based on Symbol Answer

Hello.

I'd like to know how I can setup a new scenario with a simple feature:

Use X component quantity, based on a numeric Symbol answer, for example:

I need to manage stock for a certain kind of cord for a lamp, but I can't determine the quantity of cord that needs to be "used" in that scenario based on a symbol answer.

How can I do this? I've tried to input the symbol code on the "Quantity" field, but this field is numeric only.

Thanks.