The first thing to realise is that all these numbers are multiples of the same fraction—one third. So, your number line just has to show the multiples: 1, 3, 7, 10, 15. Here’s what I would do:

Here are two number lines. The red line shows the fractions spaced out in order and the blue line shows where the whole numbers lie. So, for example, 3/3 (three thirds) lines up with the whole number 1.