The document discusses rules for determining if a whole number is divisible by other whole numbers from 2 to 13. It provides the following key points:
- A number is divisible by 2 if it is even.
- For numbers 3-9 and 11-13, various tests are provided using digit sums or differences that must be divisible by the number in question.
- A number is divisible by 10 if it ends in 0.