One question we’ve been getting from many people lately is about what the Rx BIN and GROUP numbers mean on Prescription Discount Cards. You’ll notice that all prescription discount cards utilize Rx BIN and GROUP numbers on the front. Many also feature a Member ID number, which we’ll also explain. Here’s a quick primer on what the Rx BIN and GROUP numbers mean and why they are important: Rx BIN and GROUP numbers on a Prescription Discount Card. All pharmacies use Rx BIN and GROUP numbers for processing prescription drug claims.