Lessons from Fizz Buzz

Two lessons:

$1.$ Order of conditions matters. Check the most specific case first (divisible by both) before less specific cases (divisible by one).

$2.$ If $a$ divides $n$ and $b$ divides $n$, then $a \times b$ divides $n$ (when $a$ and $b$ are coprime). This lets you combine checks.