Japanese, along with Chinese and Korean, uses counting suffixes when counting things.

• うちには車が二台ある -> We have two cars
• 私は猫を二匹飼っている -> I have two cats

The counting suffixes are different from regular nouns in that they themselves are not nouns for the target objects. Consider the below examples:

• このアルバムには十曲が収録されている -> This album contains ten songs
• 彼女は全ての曲を自分で書く -> She writes all her songs herself

Counting things, objects

There are so many different counting suffixes for different things (see the link for the list), that even Japanese native speakers struggle to use the right one from time to time. There are many Internet questions asking “what word should I use to count such and such?”.

Meanwhile 個 is the most generic counting suffix for smaller common household objects:

• りんご一個 -> One apple

Also there is another set of counting words, ひとつ (one)、ふたつ (two)、みっつ (three)、よっつ (four)、いつつ (five)、むっつ (six)、ななつ (seven)、やっつ (eight)、ここのつ (nine)、とう (ten). These can be used for most things, even though when there is a specific one instead, you can sound like a young child who has not learned the correct counting word.

• 椅子を四つ持ってきて -> Bring four chairs for me (OK)
• 椅子を四脚持ってきて -> Bring four chairs for me (technically the most correct)

However they are also used for abstract things, and in those cases they never sound childlike:

• 一つ質問があります -> I have one question
• 気になることが一つあります -> There is one thing that makes me concerned

As you may have noticed, they are only up to ten and after ten you will have to use correct counting words, even though usually that is not a big problem since you don’t count more than ten that often in everyday life.

Counting instances, repetition

回 and 度 are the most used counting suffixes for a number of instances and repetition.

• 一回、一度、試してみよう -> Let’s give it a shot
• 日本には一回、一度、行ったことがある -> I’ve been to Japan once
• 何回、何度、説明されても分からない -> I don’t understand no matter how many times it is explained to me
• 彼は三回目、三度目、で司法試験に合格した -> He passed the bar exam at the third try

They are practically interchangeable, even though 度 will be used less as the count gets higher, typically ten or more.

• 巨人は日本シリーズで二十二回優勝した -> The Giants won the Japan Series 22 times (二十二度 is not wrong, but not common)
• あの映画は五十回は観たと思う -> I think I’ve watched that movie like 50 times (you almost never say 五十度)
• 彼は腕立て伏せが五百回できる -> He can do pushups 500 times (you almost never say 五百度)

遍 is mostly used as 一遍(いっぺん) or 何遍(なんべん).

• 何遍言えば分かるんだ？ -> How many times do I have to tell you before you get it?
• 一遍試してみよう -> Let’s give it a shot