Adding a discount based on specific field

I am trying to figure out how i can apply a discount to membership fee based on specific information provided in a field. For example, i my member has a national membership number and they enter it during registration for a plan, i want to give them a 10% discount on the fee.

Is it possible to do this?

Thanks
NB

Yes that's possible. Create a coupon using CBSubs Promotions then configure a condition for that field.