The math is more intuitive if you say it decreases the failure rate. i.e. if you try something with a 10% success rate 3 times, your odds are 1 - (0.9 ^ 3) = 27

The math is more intuitive if you say it decreases the failure rate. i.e. if you try something with a 10% success rate 3 times, your odds are 1 - (0.9 ^ 3) = 27.1% chance of success.