4595
It seems to me that `千` is exceptional in having it prefixed with `一`.

  * As for `一`, `十`, `百`, they work together with `千` to describe the numbers from 1 to 9999, so they compete with one another, or are complimentary. There is no combination like:

> 一一, 一十, 一百, 十十, 十百 百百

  * As for `万`, `億`, `兆`, `京`, etc., they are multiplied by a number from 1 to 9999, expressed by the prefix using `一` `十`, `百` `千`, so when that prefix turns out to be 1, 10, 100, 1000, then they are combined, and there are combinations like:

> 一万, 十万, 百万, 千万, 一億, 十億, 百億, 千億, etc.

  * and there is no combination among themselves such as

> 万万, 万億, 億億, 万兆, 億兆, 兆兆, etc.

However, `千` is exceptional in that it is prefixed by `一` just when itself is
prefixed to the characters `万`, `億`, `兆`, `京`, etc.

> 千  
>  一千万  
>  一千億

Why is `千` prefixed with `一` in this case? Why is it not like the following?

> 千  
>  千万  
>  千億
CC BY-SA 3.0
2011-12-27T20:50:37.520
4105
2012-02-07T16:27:11.863
2011-12-27T21:19:33.350
question
numbers
Prefixing `一` to numbers
I'm mostly guessing here, but I think it might be in order not to mistake them
for 三万 and 三億 when spoken. While せんまん and さんまん only differ by a vowel, いっせんまん
and さんまん are easy to distinguish.
CC BY-SA 3.0
2012-02-07T14:26:36.393
4595
2012-02-07T16:27:11.863
2012-02-07T16:27:11.863
921
1073
4105
answer
I think the answer to this question has more to do with mathematics than
language. The point of having repeated values is to make counting easier. If
every new order of number had its own name, it would be "very" difficult to
remember them all or tell them at a glance. Also, if we didn't have new names
for each "grouped order" (not really sure what these are called), then there
would be numerous (no pun intended) ways to name one value.

What I mean is, you ask why there is (for example) no `万万`. The same reason
there is no 1,000-1,000 in English: because the order "million" has been
established. If there was no concept of millions, then the value 1000000 could
be described any number of (numerous, if not infinite) ways: 10-100000,
100-10000, 1000-1000, 10000-100, 100000-10, 500-2000, 40-25000, ...; and there
would be no consistency amongst what different people use. Since everyone
knows the concepts of millions, it's easy to instantly see and understand the
magnitude of such a value.

> Why is 千 prefixed with 一 in this case? Why is it not like the following?
>

>> 千  
>  千万  
>  千億

That's the only way I've heard those numbers. I've never heard `一千`,`一千万` or
`一千億` outside of "formal" documents, etc.
CC BY-SA 3.0
2012-02-07T16:08:53.813
4597
2012-02-07T16:08:53.813
2020-06-17T08:18:27.500
-1
78
4105
answer