From a grammar point of view, Japanese has several aspects that make it easy to learn including only a handful of tenses and relatively simple conjugations (the subject type is not used to determine the verbs conjugation like in some languages). On the other hand, there are a few areas where a student has to put in extra work, and one of those is counting in Japanese. The are various counters for different types of objects, and other exceptions like how some of the sounds change when counting one to ten verses ten to one (“4” is pronounced as “shi” on the way up and “yon” on the way down).
Just when you think you’ve learned all the exceptions there is another exception to the exceptions, which is that when expressing X or Y for consecutive numbers, you fall back to the rules for counting numbers in sequence (“ichi”, “ni”, “san”, “shi”, “go”, etc.).
For example, saying “four years” would be “４年” which is usually pronounced as “yonen”. “Five years” would be “５年”, which sounds like “gonen”. But if you want to say “4 or 5 years” you would say “４,５年” which is pronounced “shigonen”, with an optional pause between the “shi” and the “go”.
Here is a short conversation illustrating this in context.
- Person A: 日本語を何年間ぐらい勉強してるの？ ４年？５年？ [yonen? gonen?]
- Person A: How many years have you been studying Japanese?
- Person B: うん、４、５年だね。[shi, gonen]
- yeah, 4 or 5 years.
Note: When expressing durations in years you can optionally use 〜間 (~kan) as well, as in “４年間” (yonenkan).
As you may know, counting days in Japanese is also irregular (１日 => “tsuitachi”, ２日=>”futsuka”, ３日=>”mikka”, etc.). However, when expressing X or Y days, where X and Y are two consecutive days, you use the rules for counting consecutive numbers.
- ２、３日間滞在する予定です。[ni, san nichikan]
- I’m planning on staying for two or three days.
In this case, both the “2” and “3” changed the way they sound when compared to when they are pronounced separately, whereas in the year-counting case only “4” changed, because “５年” doesn’t have a special pronuncation. Since “５日” is an exception (“itsuka”), saying “４、５日” would again change and be said like “shi, go nichi”. (NOT “mi, itsuka”)
This applies to other types of counting as well. To give one more example, to say the eight floor or a building in Japanese you would use “8回” which sounds like “hakkai”. However, to say “8 or 9 floors” would sound like “hachi, kyuukai”.