Slot Machine
Slot Machines are a mini-game found in the Casino.
The player can bet either 10 or 100 Qi coins when using a slot machine. If the results match one of the winning lines, the player receives a multiple of their bet. If there is no match the player loses their bet.
Daily Luck and the Luck buff from various food items can increase the chance of winning and your expected return when gambling. Otherwise, rolls are determined by pseudo-randomly.
On a very lucky day (+.1 daily luck) and after eating a Lucky Lunch (+3 luck level) investing 
1 is expected to return 2.45.
On a very unlucky day (-.1 luck) & without buffs (+0 luck level), 1 yields 1.24 on average.
Notes
Some PC users have noticed a repeating pattern which may be exploited. The details can be viewed on the Talk Page.