As we noted earlier in Seven Days of Deals, Sampan is kicking off its lunch service with a free banh mi lunch tomorrow. Diners get a banh mi, chips and a fountain soda for free from 11:30 a.m. until 5 p.m.. There is fine print, or as the promo graphic says, there are RULES. No take-out - you must eat *in* the restaurant; seating is only available at the bar and counter and don't stiff the waiter. Oh, and this is a turn-and-burn situation, people, so don't even think about making this a leisurely lunch! So how many banh mi does a chef prepare in anticipation of five-and-a-half hours of free lunchers?

Chef-owner Michael Schulson told us they have 700 rolls, which the restaurant sources from Ba Le Bakery at Sixth and Washington, on hand for the masses. How did he arrive at this princely sum?

Using a complicated algorithm that involves taking the number of available seats, the number of guests expected and the average time it takes a human to wolf down a free banh mi. Plus, one must account for the length of the line of people waiting outside and the effects their hostile glares may have on how long it takes the folks inside to eat the free banh mi. Also, there's the pork factor. Pork is an unknown variable because it makes people do crazy things. Tally that up and it comes out to about 100 guests an hour. And that's how you do advanced banh mi math!

(Actually, it's not, but Schulson did have his own professional chef equation that involved real math for figuring it out and he told us he's anticipating serving 100 banh mi every hour.)

*Sampan, 124 S. 13th St.; (215) 732-3501*