"Perfect prime rib is an easy undertaking if you follow a few key steps. The most important is using an accurate digital thermometer. This is the only way to ensure the desired doneness, which hopefully is a perfectly pink medium-rare, when the flavor and texture are at their best. This prime rib recipe will work no matter what size roast you're using. A great rule of thumb is each rib will feed 2 guests. So, a 4 rib roast will serve 8 guests...."