Double Super Times Pay - Calculation Question

I play Super Times Pay, and Double Super Times Pay.
I was looking at the Double Super Times Pay on the wizardofodds site. It says just add 0.5% to the base return to get an accurate return.
It than gives a more accurate calculation of the formula: 1.004126984 × b + 0.000921844
I assume the "+ 0.000921844" is for the 20x on a dealt royal flush.
But I don't understand the 1.004126984. What I mean by I don't understand, is that I get a different number for the calculation.

I get 1.00190476 for my calculation.
Can someone explain to me how he got 1.004126984?

Quote: belteshazar

I play Super Times Pay, and Double Super Times Pay.
I was looking at the Double Super Times Pay on the wizardofodds site. It says just add 0.5% to the base return to get an accurate return.
It than gives a more accurate calculation of the formula: 1.004126984 × b + 0.000921844
I assume the "+ 0.000921844" is for the 20x on a dealt royal flush.
But I don't understand the 1.004126984. What I mean by I don't understand, is that I get a different number for the calculation.

I get 1.00190476 for my calculation.
Can someone explain to me how he got 1.004126984?
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Welcome to the forums, and thank you for the question, as it prompted me to work it out for myself! lol

So, let’s start with the calculation for STP, as that helped me see the more complex calculation for DSTP. In STP, we have an average multiplier of 4.05 on average every 15 hands; thus, every 15 hands, we have 14 hands at 1X and 1 hand at 4.05X. Also, we’re betting 6 for pays of 5, so the return for any STP game is 5/6 * (14*1 + 1*4.05)/15 = 1.00278 times the base return of the game without the feature.

Now, for the 99.9998% of the hands in DSTP that are not a dealt Royal, we have possible multipliers of 4.01 on either the deal, the draw, or both with the same frequency as the single multiplier in STP. As it is possible to have , neither, either, or both, our outcome space is a bit larger (15*15). Thus every 225 hands, we have 196 hands at 1X, 28 hands at 4.01X, and 1 hand at 8.02X. Here, we’re betting 7 for pays of 5, so the return for any DSTP game is 5/7 * (196*1 + 28*4.01 + 1*8.02)/225 = 1.004126984 times the base return of the game without the feature (plus the constant for the added value of a dealt Royal from both possible multipliers).