That is the positional part. If you were to rearrange it, you'd get something invalid. 二十三百 isn't a number at all. Recall that the use of zero is necessitated

That is the positional part. If you were to rearrange it, you'd get something invalid. 二十三百 isn't a number at all. Recall that the use of zero is necessitated by using positional notation, and that is what we see here: you must explicitly zero any magnitudes you're not using. (At least, any that are below one you are using.) I should also note that while there is no symbol for the number 10,000 - there is a place value, but the number is 一万, not 万 - the number 10 is still written 十.