A number line is only a representation of numbers which helps you to understand the relationships between numbers, especially helping you to grasp the idea of positive numbers (to the right of zero) and negative numbers (to the left of zero), and to compare the size of numbers, whether one number is greater (more to the right) or less than (more to the left) of some other number. So there is no start and finish to a number line: it goes on forever, as far as you like, and as far as it helps you.
When you fully understand how numbers relate to one another you won’t need the number line to help you.
The number 9200 is large compared to zero. But one way to use a number line is to divide it so that each division of the line represents 1000. So you would have 0, 1000, 2000, 3000, all the way up to 10000 represented in the same way as you would write the numbers 0 to 10. So where would 9200 be? Well it would be between the 9th and 10th divisions because 9200 is between 9000 and 10000. You would put a mark closer to the 9 than the 10 because 9200 is much closer to 9000 than it is to 10000. Let’s say you had to put other numbers on the number line: 250, 5173. 250 would sit between 0 and 1 (that is, between 0 and 1000), and 5173 would sit between 5 and 6 (that is, between 5000 and 6000). Now, when you look at the number line from a distance you can compare the sizes of the numbers. It’s like being in an aircraft and looking down to the ground. You can’t see details but you can compare positions.
So a number line can be used to sort numbers in order. And sometimes you have to go the other way: use it like a microscope for comparing quite small numbers, so the number line would be stretched.
Use your imagination to create a number line in your mind that suits the problem you are trying to work out when you are comparing numbers. You can draw the number line that you are imagining.