Source: from the TTC video course High School Algebra I with Monica Neagoy
Listen: short audio clip
So, that's numeration. Language pushed forward the evolution of numbers. But in these first two phases which are very old, what's very important to realize is that the numbers were not independent of the objects counted. So, when there were five objects, for example, there was no concept of the number five. They were just the five objects—five sheep, five people, five whatever. Then came number. The concept of number was a big step forward. It's not clear from history because we don't have enough information and research has not been able to determine when number first came into being—the concept of number. But it was clearly present in many of the great civilizations.
As you can see, there is no article, neither definite nor indefinite, in front of the word number in those two cases that I highlighted for you. How do you think that can be explained? I'm not asking you to explain this from a grammatical perspective per se, but rather from the perspective of why in this case it feels, to you as native speakers, like the right choice of words.