Demo mode runs the same maths with play money. It is the cheapest way to find out whether you enjoy the game before it costs anything.
Probabilities, payout table and multipliers are identical to the real-money version. Studios run one engine for both.
Drop several hundred balls at high risk and watch the balance rather than individual results.
Not in the maths — in the psychology. Losing imaginary money produces none of the pressure that losing real money does.
Give the demo a starting balance equal to a real session budget and stop when it runs out rather than topping it up. That is closer to the real thing than an unlimited balance, and it answers the only question worth asking: does this game hold your attention when it is not paying?