for example if you have a good strategy or alway u are playing a bias wheel or whatever is the case
my question is : is there a 'mathematical' amount where u know you have either a bias or a winning strategy

so in 500 spins: betting just one number each spin, we should win on average 13.5 wins.....
so for example if in 500 spins we won 26 times (this could be just "luck") but what amount of wins in 500 spins means bias (100 wins out of 500 spins for example???)
thanks

Look up the 95% confidence interval in statistics.