If I don’t finish reading Othello today, this puzzle is why. Since I love passing on methods of procrastination to you, here you go. Even though it’s a math puzzle, the most advanced math you need to solve it is knowledge of divisibility rules, which aren’t too advanced.
Here’s your puzzle:
Arrange the digits 1-9 such that the number formed by the first n digits in order is divisible by n.
That is, the first digit is divisible by 1, the number formed by the first two digits is divisible by 2, and so on. You should be able to figure out the place of one of the digits very quickly. The rest will take a bit more work.