Calculate the number 4451

A man walks into the front door of a bar. He is obviously drunk and staggers up to the bar, seats himself on a stool and, with a belch, asks the bartender for a drink. The bartender politely informs the man that it appears he has already had plenty to drink and that he could not be served additional liquor. The bartender offers to call a cab for him.

The drunk is briefly surprised, then softly scoffs, grumbles, climbs down from the bar stool and staggers out the front door. A few minutes later, the same drunk stumbles in the side door of the bar. He wobbles up to the bar and hollers for a drink. The bartender comes over and - still politely if not more firmly - refuses service to the man and again offers to call a cab. The drunk looks at the bartender for a moment angrily, curses, and shows himself out the side door, all the while grumbling and shaking his head.

A few minutes later, the same drunk bursts in through the back door of the bar. He plops himself up on a bar stool, gathers his wits, and belligerently orders a drink. The bartender comes over and emphatically reminds the man that he is drunk and will be served no drinks. He then tells him that he can either call a cab or the police immediately.

The surprised drunk looks at the bartender and in hopeless anguish cries, "Man! How many bars do you work at?"