Roulette
French roulette and La Partage
La Partage returns half an eligible even-money stake when zero lands on a single-zero wheel. With that rule, the house edge on those bets is 1.35%.
1.35%
Eligible even-money bets only
Single zero with La Partage
What La Partage changes
Red/black, odd/even and low/high bets are the eligible even-money groups in this model. A normal win pays 1:1. An opposite result loses the stake. Zero loses half rather than all of it.
The 1.35% calculation
For a $10 red bet: 18 outcomes earn $10, 18 lose $10 and zero loses $5. Expected net is −$5/37, or about −$0.1351. Dividing by $10 gives 1/74, or 1.351351%, house edge.
Other bets keep their normal treatment
The half-loss rule does not automatically apply to straight-up bets, dozens or columns. A standard single-number wager still has its usual 2.70% edge on the 37-pocket wheel.
En Prison needs its own rules
En Prison can hold an eligible stake over to a later spin instead of immediately returning half. The treatment of another zero must be specified. This package does not model that deferred settlement in the calculator.