There are a number of ways to cheat at the game of craps. Using fixed dice is one of the oldest methods of cheating at dice games and there are a number of ways that players can manipulate the dice. Basically, the main idea is that the dice get altered in some way so that when they are thrown, they land on specific numbers more often than others. The empty dice look reasonably fair. We computed a 94% chance of those 480 rolls as coming from completely fair dice using the Chi-Squared method. That’s pretty good for the rough surface of a 3D printed die! The two smallest magnets (3/16” B333 and ¼” B444) may have affected the results, but aren't conclusively cheating.

1. Stop The Dice Game Cheating Hidden
2. Stop The Dice Game Cheating
3. Games You Play With Dice
4. Free Dice Games
5. Stop The Dice Game Cheating Play

Archaeologists recently uncovered a 600-year-old die that was probably used for cheating. The wooden die from medieval Norway has two fives, two fours, a three and a six, while the numbers one and two are missing. It is believed that the die was used to cheat in games, rather than being for a game that requires that specific configuration of numbers.

Today, dice like this with missing numbers are known as tops and bottoms. They can be a useful way to cheat if you’re that way inclined, although they don’t guarantee a win every time and they don’t stand up to scrutiny from suspicious opponents (they only have to ask to take a look and you’ll be found out). But there are several other options of cheating at dice too, and I’ll talk you through some of them here.

It should be noted that using these methods in a casino are illegal and I’m not suggesting you adopt them in such establishments – but it’s an interesting look at how probabilities work.

For a fair die, each number has an equal one in six, or 16.67%, chance of appearing. In the case of the die found in Norway, the numbers four and five are twice as likely to appear (as there are two of them), so have a one in three, or 33.33%, chance. The table shows these probabilities.

It does not take too much imagination to see how tops and bottoms can be used to your advantage. Let’s assume that we are playing with two normal dice. There are 36 possible outcomes but only 11 possible total values the dice can produce. For example, six-four, four-six and five-five all add up to ten.

If we instead used two top and bottom dice with only the numbers one, four and five on them, we can never roll a total of 11 or 12 as we don’t have a six to make that total. Similarly, we can never get a total of three as we don’t have a two and a one. But we also cannot get any combination that would produce a total of seven, which would otherwise be the most likely total to appear with a probability of 16.67%. In a game of craps there are times when it can be really bad to throw a seven. So if you are playing with dice where a combination of seven is impossible, you have a distinct advantage.

As these kind of tops and bottoms dice will not pass even a cursory, closer inspection, they have to be brought into the game for a short time and then switched out again. This requires the cheat to be an expert at palming, meaning being able to conceal one set of dice in your hand and then bring them into play while simultaneously removing the other dice.

Using two dice, with the same three numbers repeated, might be too risky so a cheat would probably only want to switch in a single die into the game. In our example, this would mean no longer avoiding a total of seven, which would still have a probability of 16.67%. But now the totals of five and six would also have this probability.

Stop The Dice Game Cheating Hidden

In craps the odds are such that when you are required to avoid a seven, it is the number most likely to appear. Switching in a single dice can still reduce the house’s chances of winning, by making other totals equally likely to appear.

Loaded dice

Loaded dice can make cheating harder to spot. These can take a number of different forms. For example, some of the spots on one face could be drilled out and the holes filled with a heavy substance so the die is more likely to land with this face down. If you were to drill out the number one, this means that the number six is more likely to appear, as the six is always on the opposite face to the one. Another way of loading a die would be to slightly change its shape, so that it is more likely to keep rolling. This may only give a small advantage, but it could be enough to tip the game in the cheat’s favour.

With tops and bottoms it is easy to know the probabilities of various totals appearing. This is not the case with loaded dice. One way of gauging the probabilities is to toss the dice a number of times (possibly thousands) and work out what numbers appear and how often. If you know that seven is less likely to appear than it would with fair dice then, over the long run, it would be a cheat’s advantage.

Controlled throws

One other way to cheat doesn’t require an unfair die at all but involves learning how to throw in a very controlled way. This can involve effectively sliding or dropping the die so the desired number appears. If two dice are used, one can be used to trap the other and stop it bouncing. If this is done by a skilled operator, it is very difficult to see.

Dominic LoRiggio, the “Dice Dominator”, was able to throw dice in what appeared a normal way but so that they would land on certain numbers. This was done by understanding how dice travel thorough the air and controlling each part of the throw. It took many (many, many) hours of practice to perfect, but he was able to consistently win at the craps table.

Many would consider what LoRiggio did to be advantage play, meaning using the rules to your advantage. This is similar to card counting in blackjack. The casinos may not like it, but you are technically not cheating – though some casino may try to make you shoot the dice in a different way if they suspect you are doing controlled throws.

Cheating at Dice

Can magnetic dice really help someone cheat? Is this really a thing? How would that even work?

Though our handiwork isn't slick enough to fool a casino pit boss, a few experiments might help determine if magnetic dice are feasible. Let's cheat with magnetic dice!

The test subjects

We created six individual dice, each with a different sized magnet inside. We 3D printed the shapes, each with a cavity inside to hold a single cube magnet. With careful timing during the printing process, we inserted the magnet as the die was printed around it.

In each case, we inserted the magnet with the north pole facing the one, and the south pole facing the six. Each die had a subsequently larger magnet inside. The weakest has just a tiny, 3/16” B333 cube inside, whereas the largest is almost filled with the 1/2” B888 cube. Standard dice are sized as a 5/8” cube, so that last one is mostly magnet!

Can a die be a compass?

Before getting into anything fancy like a dice table rigged with an electromagnet, a more basic question has been on our minds. Would the magnet’s interaction with the earth’s magnetic field make one roll more likely than another?

The earth’s magnetic field points north, but also downward. Here in Pennsylvania, USA, the magnetic field is about 0.5 gauss, pointing north, but also at a downward angle of over 60 degrees. To learn more about that, see our earlier article, The Earth Is a Magnet.

The force from this magnetic interaction is weak. It's not enough to overcome the random bouncing around of a die, mostly. It's not going to force it to land on a six every time. Sometimes though, if the die is teetering on an edge, might this little magnetic force tip the balance more one way? In the long run, would we roll more sixes?

Roll the dice

To test the theory, we rolled the dice. A lot. Each die was rolled by multiple people, totaling 480 recorded rolls for each die. Any tendency to roll more towards one number should show up. We guessed that we’d see this effect increase with increased magnet size/strength.

With 480 rolls of each die, we expect each individual number (1-6) to show up about 80 times. We wouldn’t expect the result to be exactly 80 rolls of each number, but it should be something fairly close.

The graphs of results show:

• The empty dice look reasonably fair. We computed a 94% chance of those 480 rolls as coming from completely fair dice using the Chi-Squared method. That’s pretty good for the rough surface of a 3D printed die!
• The two smallest magnets (3/16” B333 and ¼” B444) may have affected the results, but aren't conclusively cheating.
• The larger, 5/16” B555 magnet looks fishy. For some unknown reason, a number 3 is a bit more likely than other numbers, with number 4 less likely to come up. This isn’t a clear winner as a tool to cheat with, but there’s a 1 in 3 chance there’s something fishy with those results.
• The 3/8” diameter B666 magnet is the first solid cheating die. This die is much more likely to roll a six, and less likely to roll a one. The Chi-Squared test suggests that you’d only get the rolls we recorded about 5% of the time with fair dice.
• The largest magnets were obvious cheaters. The 7/16” B777 magnet mimicked the B666, with sixes more likely and ones less likely. The B888 had a strange liking for the number 3, with over 45% more threes rolled than expected. We don’t know why, but it’s definitely not a fair die.

Why was three more likely? We're not sure, but it may have something to do with the 3D printing. All of our dice were printed on the printer's table with the three facing down. Would that affect it somehow? We're not sure.

Weigh the chances

It was a lot of fun making and testing these dice. There's one thing that doesn’t show up in the numbers: The weight isn’t right. The 3D printed plastic is lighter than regulation dice. The dice with big magnets are much heavier than regulation. If you let someone handle the big-magnet dice, they’ll know something is wrong very quickly.

Stop The Dice Game Cheating

The lightest magnet that gave us predictable results was the B666. This magnet weighs about 6.5g, which is quite a bit more than a regulation die of 4.1g. When you add the printed plastic, it’s nearly twice as heavy as normal.

Crooked Tables

With some magnetic dice to play with, it’s time to test the elephant in the room. What about a table with an electromagnet underneath? Can the house play unfairly with such a device?

If the dice is at all magnetic, then this has to be feasible. We noticed a difference in the rolls done in Earth’s relatively weak 0.5 gauss field. There has to be more influence if we increase the field strength on top of the table. What if the field were 30 times stronger?

That’s what we built. This dice table features a 5” diameter coil of 20 gauge wire. We had about 400 ft of wire to play with, which gave us 300 turns. We hooked it up to a 12V power supply, giving us about 0.6 Amps of current through the coil.

We wanted to make the coil twice as large, but ran out of wire!

Theoretically, we should see roughly 19 gauss at the center. That’s not a perfect theoretical analysis, but gets us in the ballpark. We measured about 15 gauss at the table surface, so close enough.

How effective is 15 gauss? Too much! In the center of the circle, the dice with the four largest magnets won’t stay down on any number adjacent to six. Set it down on a 2, 3, 4 or 5, and the dice will jump to display a 6. This is a little too obvious!

It will set down on a one, even if it’s unlikely to land on a one during a roll.

Games You Play With Dice

This is too strong to leave turned on all the time. Dice that land more often on one number will be easy to spot very quickly. A setup this strong would only be turned on occasionally to fool people, only getting the six for a key roll.

Free Dice Games

We didn't make it very large, but the coil could just as easily be much larger. It could be made as large as the table! We skipped this step because that would take a lot more wire, which can be expensive. For a proof-of-concept, we worked with materials at hand.

Disclaimer

Stop The Dice Game Cheating Play

Please, do not cheat at dice. Don’t blame us for getting kicked out of a casino! We don’t promote making crooked dice. As always, this exploration was really just an excuse to play with magnets.

If you notice your dice stick to steel, though, somebody might be cheating.