一人ひとり・二に本ほん・三さん冊さつnumbers and counters

Which counter?

Not sure which one? つ is understood for almost any object. It never counts people or animals.

Where the number goes

English puts the number first: "three magazines". Japanese usually names the thing, gives it its particle, and then says how many.

The noun already has its particle, so the number gets none.

You will also see the number in front of the noun, joined by の.

When it is clear what you are counting, the noun can go. When people order, を often goes too.

Readings that change

Most numbers and counters simply join: 二に枚まい, 五ご台だい, 九きゅう回かい. These are the ones that don't.

いっぽん, さんぼん: counters that begin with h, k or s

One, eight and ten are clipped to いっ, はっ and じゅっ, and six to ろっ in the first two columns. In the first column the counter changes too: h becomes p after a clipped number (いっぽん, いっぴき) and b after three and after 何なん (さんぼん, なんびき).

The numbers not shown are regular: 二に本ほん, 四よん本ほん, 五ご本ほん, 七なな本ほん, 九きゅう本ほん. Before a counter, four is usually よん, seven なな and nine きゅう.

ひとつ, ふたつ: the older numbers

つ has its own numbers, an older set than いち, に, さん: 一ひとつ, 二ふたつ, 三みっつ, 四よっつ, 五いつつ, 六むっつ, 七ななつ, 八やっつ, 九ここのつ, 十とお. They stop at ten, and ten has no つ. From eleven on, people usually switch to 個こ: 十じゅう一いっ個こ.

つ also counts what you order in a café, and things you can't touch, like a question or a problem.

ひとり, ふたり: people

One person and two people use the older numbers. From three it is 人にん: 三さん人にん, 四よ人にん, 五ご人にん. Four is よ here, not よん.

Restaurant staff ask with 名めい様さま, a polite counter for customers. You answer with plain 二人ふたりです.

ふつか, みっか: days

The second to the tenth of the month use the older numbers too: 二日ふつか, 三みっ日か, 四よっ日か, 五いつ日か, 六むい日か, 七なの日か, 八よう日か, 九ここの日か, 十とお日か. The same words count days: 三みっ日か is the third, and also three days.

Four more to learn whole. The first of the month is 一日ついたち, though one day is 一いち日にち. The fourteenth is 十じゅう四よっ日か, the twentieth 二十日はつか and the twenty-fourth 二に十じゅう四よっ日か. The rest are the number and 日にち, with seven read しち and nine く: 十じゅう一いち日にち, 十じゅう七しち日にち, 十じゅう九く日にち.

よじ, じゅっぷん: the clock

On the clock, four, seven and nine are 四よ時じ, 七しち時じ and 九く時じ. 分ふん is ぷん wherever 本ほん changes, and after four too: 一いっ分ぷん, 三さん分ぷん, 四よん分ぷん, 六ろっ分ぷん, 八はっ分ぷん, 十じゅっ分ぷん, 何なん分ぷん. It is never ぶん.

さんびゃく, はっせん: hundreds and thousands

These change: 三さん百びゃく, 六ろっ百ぴゃく, 八はっ百ぴゃく, 三さん千ぜん, 八はっ千せん. The others are regular: 二に百ひゃく, 五ご千せん.

100 is 百ひゃく and 1,000 is 千せん, with no 一いち in front, but 10,000 is 一いち万まん. Above that, Japanese counts in 万まん where English counts in thousands: 30,000 is 三さん万まん, and 100,000 is 十じゅう万まん.

Asking how many

何なん takes the counter you expect in the answer. いくつ goes with つ, and いくら asks a price.

For someone's age, 何なん歳さいですか is the plain question and おいくつですか the polite one.

Three to learn whole