Whole numbers less than 20 are 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1. How to know if they are divisible by 3? Add the numbers, and if the sum is divisible by 3.
There is an infinite number of numbers between 0.33 and 0.34 for example, 0.331, 0.332, 0.3321213323, 0.3333333, 0.3336778, etc. There should be more to the question.
