Math Trades

With the fall Granite Game Summit fast approaching, it’s time to launch the next no-ship G2S Math Trade. At first glance, a Math Trade can seem daunting: GeekLists, submission deadlines, wantlists, the Online Wantlist Generator (OLWLG)...but with a little patience and some guidance, you’ll find them to be an excellent way to trade your games.

What is a Math Trade?

The basic premise of a Math Trade is simple - you get a group of people looking to make trades together, figure out what people want, and figure out a way to make the most trades. We’ll talk about how the actual trade will go down in a little bit, but let’s just give a quick example of the theory behind a Math Trade:

Person A has a copy of Ticket to Ride for trade, and wants a copy of Lord of Waterdeep. Person B is trading a copy of Lords of Waterdeep, but has no desire for Ticket to Ride. She would, however, like a copy of Luna. Person C? Well, he’s looking to trade Luna and has his eye on a copy of Ticket to Ride. 

As you can see, none of these gamers can trade with just one other person. But their wants are fairly closely aligned with one of the other traders. So that means that if they work together everyone can get what they want.

Person A gives Ticket to Ride to C and gets Lords of Waterdeep from B
Person B gives Lords of Waterdeep to A and gets Luna from C
Person C gives Luna to B and gets Ticket to Ride from A

That sounds complicated, how does it work?

To make all of this easier, we utilize BoardGameGeek’s GeekList feature. When someone wants to set up a trade, the moderator posts a trade GeekList, along with any rules for that math trade. Anyone interested in joining the trading posts the game or games that they would be willing to trade as items in the GeekList. This will go on until a predetermined point, at which time the GeekList is closed to new game entries.

Now comes the fun part! Everyone that submitted a game for trade will take a look at the GeekList and decide which game they would be willing to trade their offering for. If they have more than one item in the trade, they will select desired items for each one. This process forms their “wantlist”, which is submitted to the moderator to determine which trades take place. 

As a side note here, this part sounds very complex, but is made far easier by the OLWLG tool, which automates the process of collecting want lists for all the users. The GeekList for the trade will have links in it for the OLWLG, and there plenty of helpful tutorials out there if you need assistance. 

This wantlist submission period will take place for a preset length of time, at the end of which no additional submissions will be accepted. Once the moderator has all the submitted wantlists, they run the algorithm to find out who should send their game to whom. This algorithm is typically configured to maximize the total number of trades. Of course, as we’re doing a “no-ship” Math Trade, we just bring our items to the G2S event!

Once this is complete, the moderator posts the list of trades as decided by the algorithm. It’s important to realize that there will be game entries that won't be traded at all. Either no one wanted the item, or the owner decided that nothing piqued their interest enough to trade. For the games that DID trade, you'll be told whom to give your game to and which game you'll be getting in return (and from whom). Chances are good that you'll be getting your new game from someone other than the recipient of your old game.

So if you’ve got some games on your shelf that need to find a better home, or just want to get some new blood into your collection, think about the G2S Math Trade. And if you have any questions about Math Trades, feel free to drop me a line and I’ll see if I can help! 

Today's guest post was written by Dan Cristelli of Board Everyday. Dan will be attending #G2SFall16 and running our math trade for us. You can follow Dan on Twitter: @boardeveryday or email him at if you have any questions. To take part in the math trade, or find out more information you can go to: