When No Demo Exists
Plenty of builds in this category go straight to a deposit prompt, and the absence of a practice mode is not proof of dishonesty on its own. There is still a free way to learn: watch live rounds settle without betting. The timer, the history strip and the payout figure are all visible to a spectator, and twenty minutes of watching teaches the mechanics as effectively as playing them with fake credits.
What it cannot give you is the reference payout figure from your own session — but the published payout table serves the same purpose provided the build has one. A build with neither a demo nor a published payout is a build with nothing to check, which is itself the conclusion.
Demo Balances Are Not Money
Practice credits cannot be withdrawn regardless of the number displayed, and a site offering to convert demo winnings into a real balance is running a promotion with wagering conditions attached. Those conditions, not the conversion, are the actual offer — and they usually require turnover several times the amount before anything can leave the account.
For what the practice rounds are teaching you about, see the format defined. For the arithmetic the hundred-round drill makes visible, read the payout breakdown on the home page.