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# How do the number of coins played affect payback percentages?

30 August 2008

I'm a little confused. If the RNG is the only thing that controls the outcome on a slot machine, then how do the different amounts you play enter into the payback percentages?

Leese

Dear Leese,

The only thing the number of coins you played affects is how much you get paid for winning combinations. As you said, the number of coins played has no effect on the symbols that land on the payline.

PC (percentage calculation, also called PAR) sheets for multi-coin machines has multipler lines showing the long-term payback percentage for the number of coins played. The long-term payback percentage can change if betting additional coins activates new winning combinations or entitles you to a bonus on one or more combinations.

Let's take a 2-coin machine with a long-term payback of 95%. The quoted long-term payback numbers are always for full-coin play. If this 2-coin machine is a Double Diamond machine on which the two-coin payouts are exactly twice the one-coin payouts (a straight multiplier), the one-coin long-term payback percentage will be the same as the two-coin long-term payback percentage.

If this machine, however, is a Bonus Multiplier, which pays a bonus for full-coin play on one or more combinations, then the one-coin long-term payback percentage will be below the two-coin long-term payback percentage. Let's say the jackpot pays 2,000 coins for two-coin play and 800 coins for one-coin play. There's a 400 coin bonus for the jackpot on full-coin play. The long-term payback percentage for one-coin play might be only 94.5% on this 95% long-term payback machine.

Let's say this machine is a Buy-A-Pay machine and playing one coin buys the bar combinations and playing the second coin buys the combinations with 7s. The long-term payback for playing one coin can be different from that for playing two coins because you don't win on the 7s combinations when you play only one coin.

There are two parts of the long-term payback calculation. One part is how frequently combinations land on the payline. The other part is how much you are paid for the combinations. The number of coins played does not affect the frequency with which combinations land on the payline, but it does affect how much you are paid for the winning combinations.

To summarize, the number of coins you play has no influence whatsoever on the symbols that land on the payline. The number of coins played can affect long-term payback percentages, however, because it affects how much you are paid for combinations.

Best of luck in and out of the casinos,
John

Send your slot and video poker questions to John Robison, Slot Expert, at slotexpert@comcast.net. Because of the volume of mail I receive, I regret that I can't reply to every question.

John Robison

John Robison is an expert on slot machines and how to play them. John is a slot and video poker columnist and has written for many of gaming’s leading publications. He holds a master's degree in computer science from the prestigious Stevens Institute of Technology.

You may hear John give his slot and video poker tips live on The Good Times Show, hosted by Rudi Schiffer and Mike Schiffer, which is broadcast from Memphis on KXIQ 1180AM Friday afternoon from from 2PM to 5PM Central Time. John is on the show from 4:30 to 5. You can listen to archives of the show on the web anytime.

#### Books by John Robison:

The Slot Expert's Guide to Playing Slots
John Robison
John Robison is an expert on slot machines and how to play them. John is a slot and video poker columnist and has written for many of gaming’s leading publications. He holds a master's degree in computer science from the prestigious Stevens Institute of Technology.

You may hear John give his slot and video poker tips live on The Good Times Show, hosted by Rudi Schiffer and Mike Schiffer, which is broadcast from Memphis on KXIQ 1180AM Friday afternoon from from 2PM to 5PM Central Time. John is on the show from 4:30 to 5. You can listen to archives of the show on the web anytime.

#### Books by John Robison:

The Slot Expert's Guide to Playing Slots