If your game uses dice, or similar random number generators, you should have enough understanding of probability that your mechanics actually do what you intend. I've encountered several home-brewed RPGs that could not manage that.
Be aware that trying to fool your players with mathematical tricks is not a good idea. I was once asked to help design a dice-pool mechanic for a cinematic game where taking more dice in exchange for a higher target number would give the impression of taking greater risks, but actually increase the probability of success. Even if the players didn't spot this instantly, they'd soon learn from experience that doing this made things easier, which would destroy the tension the mechanic was supposed to create.
If you have a copy-editor, which is always a good idea, they should try to clean up statements that are mathematically dubious or ambiguous. For example, in d20-based games, some people will think that "+1 to hit always increases your chance of hitting by 5%." Well, yes, in one sense that's true. But if your chance was only 5%, adding 5% doubles your chance. The problem is with the boundary between English and mathematics, and avoiding the pitfalls along that border is a good idea.