Can you replace the question mark with a number?

A Texas cowboy went to the dentist with a toothache. After an exam, the dentist told the cowboy he had a tooth that had to come out.
"I'm going to give you a shot of Novocain," the dentist explained, "and I'll be back in just a few minutes."
The old cowboy grabbed the doc's arm and said, "No way! I hate needles and I ain't havin' no shot!"
The dentist said, "That's ok, we'll just go with gas instead."
The cowboy replied, "Gas makes me sick! I ain't havin' no gas either!"
Without saying a word, the dentist turned and left the room for a minute, and when he came back, he handed the cowboy a glass of water and said, "Here, take this pill."
The cowboy looked at the pill and asked, "What is it?"
The dentist replied, "It's Viagra."
The old cowboy looked surprised and asked, "Will that kill the pain?"
"No," replied the dentist, "but it'll give you something to hang on to while I pull that tooth."