The hits and therefore win increases linearly with additional paylines, hence the bet is similarly increased to keep the RTP constant.Īs hits for scatter combinations are independent of paylines their prizes are multiplied by the bet to keep the RTP constant. The number of paylines and their layout is usually of little concern mathematically, as the RTP tends to be independent of the number of paylines in the game in Excel the RTP is usually calculated for a single payline only. This is also referred to as prioritization, as we order the priority of the pay rules, and determine which single rule to pay. While we could pay both, it is more common to pay on the highest win only, hence the common rule on slot games of “Highest win pays on each payline”. This is commonly referred to as a left to right combination, and we can write it as the combinations respectively). We can add a second pay rule to the game in Figure 1, which wins 100 credits when we get A on the left 2 reels, but not on the 3rd reel.

We can also see that as the chance of winning increases the prize won must correspondingly decrease to achieve the same RTP. Indeed, their volatility is so extreme that neither would be a practical design. The game that wins every time has a very low volatility, and the other a very high volatility. The key difference between these two games lies in their volatility. These two games have the same RTP, yet would be fundamentally different to play.

In the previous section we also calculated a RTP of 100% for a game that wins 1000 credits once in every 1000 games, and zero every other play. If we have a game that wins 1 credit for every play, the average win is then 1 credit, and with an average bet of 1 credit this gives us an RTP of 100% (Equation 3).

Slots machine matching reels