New European system of Bistromathics

Bistromathics was Douglas Adams' term for the crazy difficulty of dividing up l'addition at a restaurant properly. The very rules of math seem to go wrong, which is why they were able to make a stardrive as long as the ship had a bistro in it.

When groups go out to dinner, many people feel that "Div N" is the safest way to go. Namely divide the total bill with tip by the number of folks and everybody pays that. It has the advantage of great simplicity, avoiding the bistromathics. And it is close to a must with shared dishes and the norm for Chinese/Indian.

For many people, Div-N balances out over time, but many people resent Div-N for various reasons:

  • For non-drinkers, they are bothered at paying a bar tab that often is as big as the food tab. Sometimes two totals are given because of this.
  • For vegetarians, not only are their dishes usually cheaper, but many have an ethical problem with paying for other's meat.
  • Dieters are as they are due to lack of self-control. Many have a compulsion that bothers them if they pay for food but don't eat it. (Larger restaurant portions are blamed by some for the obesity epidemic.)
  • Women tend to eat less than men, causing a sex-bias.
  • Some are just plain poor, and can't handle the high Div-N bill. Because Div-N encourages liberal ordering of expensive dishes and apetizers, it tends to raise the overall price.

Often there will be somebody (frequently of low income) who wants to break the Div-N rule and pay just for what they ordered. My rule for this now is to hand them the bill and say they are responsible for calculating and collecting the bill for everybody. I do this because there have been times when I have been the banker that people have announced they will only put in for what they ordered after much of the div-N payment has been done. While one can sympathise if they only ordered $10 of food and div-N is $25, what they are asking is that the banker now take the loss. This is why they should become the banker.

I was told last year of a new system which is gaining popularity in Europe. It works as follows. One diner is indeed the banker. The bill is passed around and each is told to put in "what they think they owe." The banker takes the pile of money and does not count it. It is made very clear that the banker will not be counting, at least not at the table. The banker then pays the bill out of their own wallet, usually by credit card, though sometimes with cash. To avoid counting, paying with cash should typically be done by just taking out a modest number of the large bills from the stack if the banker is short. If there is a shortfall, the banker loses out. However, those who described this system to me say that, based on experiences of bankers counting after they leave the restaurant (declasse as this may be,) the banker typically comes out of it a winner, often getting their meal for free, sometimes even making money on top of that. This, it is presumed, is because the people in the dining party tend to overcompensate, knowing that paying in low means cheating somebody they know, and not a faceless pile of money. This more than makes up for people who are bad estimators or misers.

The real beauty of this system is that everybody goes away happy. Nobody has put in more money than they felt was fair. Bankers may lose out a few times but on balance, it is reported, come out fine. The restaurant only gets the tip the banker announced. In other systems sometimes they get a windfall. The main downside is it does require people to have a sense of the cost of what they ordered, or they have to look through the bill which takes time.

I have yet to have the guts to try this, though. Some doubt it would work with people in the USA. Some suspect it will only work among those of reasonable means, or among good friends. Hard to say.

Of course, restaurants could also just not be so resistant to separate cheques. So many of them look at you like you've popped a 3rd head if you ask for it. Sure, it's more work but it's not like it's rocket science, especially since so many places have computers to handle the bill. One could even design paper billing systems that make it easy to do the individual accounting. Many groups of diners would also happily volunteer to tip (or plain old pay) an extra 50 cents/person for separate cheques. Even if it takes 1 minute extra per person to do the accounting, which I doubt, that's $30/hour for the work.

Updated note:

Now there is one reason for this. When a meal is done Div-N, people are encouraged to order more food, and more expensive dishes, since it makes very little difference in what they will pay. That's very good for the restaurant, and so they want to encourage both Div-N and expense accounts which cause the same thing. If this European system caught on, they might find it becomes worthwhile to do separate cheques. Separate cheques are important for things like group meetings, where there is no central sponsor, and the people gathering don't know one another very well (or at all.) Some groups I know that meet at restaurants end up either getting a deal for separate cheques, or limit themselves to cafeteria style restaurants where each person orders for themselves at the counter. That's a shame.


I wish this system worked. But my experience is that if you just let people put in what they think they owe, the total collection is almost always short. Way short. I think the problem is that people pay what they remember seeing on the menu, and don't bother to factor in drinks, tip, and tax -- or do so inaccurately.

Ok, so why am I told it works in Europe? You've actually tried it here, including the (I think very important) rule that it is made clear the banker will not be counting, and if you underpay, you are stiffing a friend? As it was explained to me, this is what makes the difference and causes people to overpay.

There certainly are people willing to overpay. With Div-N, sometimes we see a short pot -- which can't be any sort of mistake, it is probably an anonymous protest by somebody who ordered cheap -- there are always folks willing to chip in a bit more, perhaps because they feel they got a deal with Div-N. But fairly often there's a fat pot, which goes to the restaurant, or perhaps from time to time to the person who wants to wield their card.

(Some more comments on Div-N added to the main article.)

Menu prices in Europe already include VAT don't they? And aren't tips lower percent too? Often in the US sales tax on restaurants is near 10% and a 20% tip is added to the bill for groups. Then the iced tea wasn't on the menu and costs twice what you expected. Very quickly you have to put in $20 to cover a $10 item. If US menus listed the price after tax and tip, I suspect Bistromathics would work okay here too, at least for groups that dine together often. But of course, the sticker shock would be a problem.

Although everybody has a calculator with them in their cell phone these days, but at least for now most would not know how to get to it. I did find in Australia, where the price shown on the menu is the price you will pay, with tipping uncommon and tax included, that there was indeed sticker shock, especially combined with the cheaper dollars. An item that is $10 in the USA might say $20 in Australia. And while you know it's the same, if you go by a restaurant and the menu shows all the main dishes are $40 it's hard to break the programming that says "this is a fancy restaurant, only go in if seeking such."

Go to the source, maybe? The bank system you described is Stowe Boyd's -- and he's very american: (check the trackbacks for more on the topic, there was a whole discussion).

So, yes, of course this works in the USA. That is where it was devised.

Yes, I am at least the proximate cause of the use of the system in Europe, since I have been scurrying around having dinner parties everywhere. Your piece has led me to rename the system from "being the Bank" to "Bistronomics" based (partly) on the "Bistromathics" term (which is a mouthful).

See Being The Bank, AKA Bistronics:

My recollection was that I had heard this as having become popular in Europe well before your July blog post, so it may have had many fathers, and indeed, commentors on your blog report also having done it. However, you may indeed have been the indirect source, as my memory is dim as to who told me.

I called it European because I have not seen people be very warm to it when suggested in the USA, and heard reports of greater warmth in Europe.

Of course the term bistromathics is well understood in geek circles, but I am not sure whether it's good for the name or not, because as Adams defined it, bistromathics was based on the fact that you could never get the numbers to work out right on a bistro bill.

I've used the banker system many times with friends, here in the US, and it works fine. there is also the method of One Person Treats, basically meaning that the poorest person backs out of paying with the promise that they will cover everyone for the next meal. Generally this next meal turns out to be very expensive, so this method keeps everyone in line with the not paying. since we are all good friends (or equal bastards, i'm not sure which) it all works out in the end.

I'm not clear. Why would somebody of low income agree to pay for an entire expensive meal, just to get out of a 1/N share of a lesser meal? I can't see that ever making sense. Or are they agreeing only to pay 2/(N-1) at the next meal? That would make sense for somebody who is just a little short one week.

We don't seem to have the problem with people being short of cash because the restaurants mostly will take more than one credit card in a pinch, and the latest innovation is that you ask somebody to cover you, and you paypal them the money when you get home. Or even from your cell phone. (Paypal's original business plan involved payments from PDAs in fact.)

It's a matter of wealth.

I've found that being banker in the "dont-count-it" method is to my great advantage when I'm having a meal with a group of people who consider themselves well off. People employ the 'Yuppie Dining Coupon' method is employed even at a light lunch. On the other hand, folks who are a bit more desperate tend to scrimp. Folks who game the system too often are snubbed.

If one cares about the money, I guess one could pick the method for the crowd.

I regularly hang out with people who have widely disparate incomes (meals after Critical Mass especially, combo of geeks and students) and the banker system works pretty well in that situation. Although we normally call it "the donation tin". We bulk order and accept donations, and the extra goes into the donation tin for next time or "other things" (Critical Mass does "other things" quite well). A while ago we did that after mass and made ~20% of the total in "profit".

I think it's partly because we eat at cheap places, and partly because there are enough geeks to cover the shortfall. It only takes ~10% of the people to pay 50% over the actual and you're square. This also covers the small change problem - few people are capable of both adding up what they ate and finding exactly $7.65 in their wallet, but for the banker that missing .15 or .65 adds up over 20 people. Plus here we don't have the hidden fee nonsense that you have to put up with, so people have a better idea of what they've "spent". We do have a degree of haggling ability though, and I gather that's also rare in the US. "haggling" and "asking for a discount" depending on whether you're asian or anglo. So if we get $220 worth of food but I only get $200 from the group I will often say "group order, how about a discount"... sometimes I get it. Other times, we just get a deal automatically, like ordering 30 pizzas for pickup at 7:30pm on a Friday (after Mass) we get the "Tuesday lunchtime special price".

I suspect you're also used to much more expensive meals than I am, which does change the dynamic. I'm quite willing to pay $200-odd in the expectation of getting it back but it's no great risk to me personally if I don't. But if that was $2000 I'd be much more reluctant to take the risk. I think partly because I associate that with much bigger gatherings where there are less direct personal links. I just can't imagine paying over $100 a head for a meal...

Or more accurately, whoever issued the invitation pays for everything. This solves any problems dividing up the bill.

It also makes for some interesting dynamics as diners compete to pay the bill.

In work situations, the manager puts the bill on their corporate credit card.

Curious. When I visited Hong Kong, and found I could not find the good restaurants, I took to calling up people I knew barely (such as people on my customer lists) to ask them to lunch. I intended to pay (and the custom in much of the world is that if a vendor invites a customer to lunch, the vendor always pays, though of course the customer is paying indirectly.) I did this only so they would direct me to good places to eat, and for some company, and that part worked -- but to my embarrassment they insisted on paying, saying they were the hosts and I was the visitor to their town.

Tried it many times. Never worked a single time.

Everybody appreciates service differently. Some will tip. The banker usually sees a profit for himself instead of the person who earned it, and refuses (even as acknowledged in your post and again in several of the comments) to contribute on an equal footing (i.e. refusing to put in what they think they themselves owe, even if the bank is "over" what they personally think the waitress deserves).

Sure, if everyone in the group are jerks, it can work. Otherwise, it's doomed to misdirect funds away from the one who earned them.

As I outlined it, the banker must declare what the tip shall be (or perhaps declare tax + tip since most people will remember the menu-prices of their items) and the table gets a chance to argue it up or down, but one it is set, the expectation should be that any fair payer must not stint on this. Though I would have thought you could allow people to go up or down from a base tip.

Now, if your declaration that it doesn't work (in your situation) is true, then the banker is indeed taking a risk, and so having the rare profit go to the banker does not seem unfair, if they're taking the more common loss. But yes, the system is that the banker is the one person who doesn't calculate what they owe. They just pay what it say son the bill, plus the tip they declared, and don't count the money or calculate their own meal. That is the reward/punishment for being banker.

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