Roulette literacy
The zero belongs in the calculation
Roulette layouts, probability and the mathematics of independent outcomes. No systems that promise to beat the wheel.
State the model
Consider an ideal single-zero roulette wheel with 37 equally likely pockets: numbers 1 through 36 and one zero. A straight-up wager on one number therefore succeeds with probability 1/37. The Massachusetts roulette rules provide a concrete published example of a 35-to-1 straight-up payout. These assumptions matter; a different wheel or payout requires a fresh calculation.
Separate profit from return
For a hypothetical one-unit stake, a winning result produces 35 units of profit and returns the original unit. A losing result costs one unit. Expected net change is therefore (35 × 1/37) − (1 × 36/37), or −1/37 of a unit. Expressed as a percentage of the stake, that is approximately −2.70 percent.
Keep the scale honest
This average describes the model across repeated trials. It does not predict the result of a particular spin or promise that a short session will finish near that figure. Write the pocket count and payout beside every quoted percentage.