the machine
Five credits a pull on one payline. There is no stake and no prize. The reels run on real weighted virtual stops, and the panel beside them prints what actually happened on every pull, including the ones that were built to feel like they nearly came in.
CATABU . one payline . max bet 5
credits500
the audit
Pull it once and this panel starts telling on the machine.
Count the symbols on a reel and three sevens looks like 1 in 10,648. Behind each reel is a weighted list of 67, 69, 73 virtual stops, and the seven owns one entry on each. The real answer is 1 in 337,479, about 32 times longer than the reel is telling you.
Method: US patent 4,448,419, Telnaes, 1984.
On any given pull a seven is sitting in the window on reel one 25.4 percent of the time, because the stops either side of it are the heaviest on the machine. All three reels show one and pay nothing on 2.20 percent of spins, which is 1 in 45.
Near misses are rated worse than plain losses and make people play on. Clark et al, Neuron 61(3), 2009.
That is what this machine gives back over every possible outcome, worked out by enumerating all 10,648 of them rather than by simulating. Nevada will not license a slot machine that returns less than 75 percent. This one is 0.54 points short of being legal in a casino.
Nevada Gaming Commission Regulation 14.040.
16.0 percent of pulls hand back less than the 5 you staked, which is more often than every other kind of win put together. The audit calls those out by name. A real machine plays a fanfare instead.
Dixon et al, Addiction 105(10), 2010.
Per pull, at the 5 credit stake. The odds column is exact, not a rounding of a simulation.
| on the line | pays | lands |
|---|---|---|
| 777 | 50,000 | 1 in 337,479 |
| 12,000 | 1 in 42,185 |
| 2,000 | 1 in 12,499 |
| 900 | 1 in 1,562 |
| 155 | 1 in 195 |
| 110 | 1 in 100 |
| two sevens, reels one and two | 100 | 1 in 4,687 |
| any three pictures, no blank | 4 | 1 in 6 |
Left is what is painted on the drum, all 22 positions of it. Right is how many virtual stops each position owns on each of the three reels. The bar is the third reel, the one that stops last.
| stop | symbol | reel 1 | reel 2 | reel 3 | |
|---|---|---|---|---|---|
| 0 | seven | 1 | 1 | 1 | |
| 1 | blank | 8 | 9 | 11 | |
| 2 | cat | 3 | 3 | 3 | |
| 3 | die | 3 | 3 | 3 | |
| 4 | cards | 2 | 2 | 2 | |
| 5 | blank | 3 | 3 | 3 | |
| 6 | cat | 3 | 3 | 3 | |
| 7 | halo | 1 | 1 | 1 | |
| 8 | die | 3 | 3 | 3 | |
| 9 | blank | 3 | 3 | 3 | |
| 10 | cat | 3 | 3 | 3 | |
| 11 | cards | 2 | 2 | 2 | |
| 12 | coin | 3 | 3 | 3 | |
| 13 | blank | 3 | 3 | 3 | |
| 14 | cat | 3 | 3 | 3 | |
| 15 | die | 3 | 3 | 3 | |
| 16 | halo | 1 | 1 | 1 | |
| 17 | blank | 3 | 3 | 3 | |
| 18 | cat | 3 | 3 | 3 | |
| 19 | cards | 2 | 2 | 2 | |
| 20 | die | 3 | 3 | 3 | |
| 21 | blank | 8 | 9 | 11 |
Run node tools/paytable.mjs in the repository and it will print every figure on this page from that table alone.