I will update help page, but not going to change math to something inconsistent.
The payout multipliers you're quoting aren't the payout multipliers you offer.
What you're doing would be like a casino saying "we pay out 38x on a single roulette number" (because that's what they would pay out if the house edge was 0%, but it isn't).
Then someone hits a single number and the casino pays out only 36x.
The player complains "you said 38x but I only got 36x", and you reply "you forgot the house edge!"
What really happens is the casino tells the player "we pay out 36x on single numbers".
That way it's clear what you're getting.
I updated help page to reflect order of operation. The multiplier on the page is what the actual multiplier is.