68588
On a news report, I heard the phrase 四五{しご}十{じゅう}メートル and it got me thinking
about how to express other number approximations. Are the following correct?

  * 10 or 20 meters じゅうにじゅうメートル 
  * 20 or 30 meters にさんじゅうメートル
  * 30 or 40 meters さんよんじゅうメートル
  * 40 or 50 meters しごじゅうメートル
  * 50 or 60 meters ごろくじゅうメートル
  * 60 or 70 meters ろくななじゅうメートル
  * 70 or 80 meters ななはちじゅうメートル
  * 80 or 90 meters はちきゅうじゅうメートル
  * 90 or 100 meters きゅうじゅうひゃくメートル
CC BY-SA 4.0
2019-05-30T12:59:52.870
68582
2020-03-12T01:49:04.073
25875
question
numbers
What is the correct expression of 10/20, 20/30, 30/40 etc?
いちに, にさん, さんよん (or さんし), しご, ごろく, ろくしち (or ろくなな) and しちはち (or ななはち) are very
common and handy expressions. はちきゅう is understood, but is relatively less
common. We don't use よんご for some reason. They are used like this:

  * いちにかい: once or twice
  * にさんにち: 2 or 3 days
  * さんよんまんえん: 30000-40000 yen
  * ごろっぴゃくねん: 500-600 years
  * しちはっぽん: 7 or 8 (e.g. pencils)

It's even possible to say:

  * よんじゅうごろっキロ: 45-46 kg/km
  * せんろくななひゃっかい: 1600-1700 times

But じゅうにじゅうメートル and きゅうじゅうひゃくメートル are wrong. In these cases, you have to use
から (or [ないし](https://japanese.stackexchange.com/q/46524/5010)) explicitly and
say:

  * じゅう から にじゅうメートル: 10-20 meters
  * きゅうじゅう から ひゃくメートル: 90-100 meters

You also have to use から explicitly when you want to say 50-70, for example.

  * ごじゅう から ななじゅうえん: 50 to 70 yen  
(ご から ななじゅうえん is also acceptable when there is no chance for misunderstanding)

Related: [How to read: the "~" (tilde) in "3~4
行"](https://japanese.stackexchange.com/q/21679/5010)
CC BY-SA 4.0
2019-05-30T17:58:51.200
68588
2020-03-12T01:49:04.073
2020-03-12T01:49:04.073
5010
5010
68582
answer
My speculations, but:

Might also be related to the fact that 10-20 is such a rough value that the
person asking the question might be expected to know that. On the countrary,
70-80 or 80-90 are too tight tolerances in normal circumstances.

(Naruto-san, watch your speed! I guess the only circumstance you would use
45-46 km/h would, I think, normally only be used if you get caught speeding on
a 30 km/h street and the police asks you how fast you were driving).

What does not sound logical (but may be related to similar reason why we have
60 mins in 1 hour) is that for any distance in meters even close to 600m one
would use that. (Or say 500-600), but instead of saying "about 500m" one
normally chooses to say "about 600m"

Tuomo
CC BY-SA 4.0
2019-06-05T14:33:35.783
68682
2019-06-05T14:33:35.783
34261
68582
answer