Multiplier is calculated by (65536 / Game Lessthan). Previously, that number was rounded down then truncated after 3rd digit, but now it is either rounded up before truncate, or simply truncated.

I take house percentage after multiplier is calculated as doing it other ways (ex. as part of multiplier) are inconsistent in results. Edit: To make clearer, it makes results inconsistent from game to game, or with largely different bet amount, and not always in favor of user.

Satoshidice shows multiplier less the house percent. I show multiplier prior to house percent.

I don't run satoshidice so I can't say how they do their backend maths, but I know payout (housecut, etc) is not consistent from game to game on their site.

Mine is: ((Bet * Multiplier) * (.9835)) - 0.0005