>This works for most people, because if you have under 30 kids, you have a good chance of never getting a kid who is on the 1% level of difficulty (Rule of 1/3n

>This works for most people, because if you have under 30 kids, you have a good chance of never getting a kid who is on the 1% level of difficulty (Rule of 1/3n). What is the "Rule of 1/3n?"