Numbers in Japanese: counting 1 to 10 and beyond, kanji and counters

Two ways to count: Sino-Japanese and native numbers

The numbers in Japanese come in two sets for one to ten. The Sino-Japanese set, ichi, ni, san, came with Chinese writing and is the one used for arithmetic, prices, dates, telephone numbers and everything above ten. The native set, hitotsu, futatsu, mittsu, is older Japanese and survives for counting things up to ten, especially objects without a counter of their own: 一つ hitotsu, one item, 二つ futatsu, two items.

The native set stops at ten, tō. Ask for eleven apples and the Sino-Japanese number returns, joined to a counter. Ten is the ceiling: the native numbers cover small quantities only.

Both sets are written with the same kanji. 三 is san in 三月 sangatsu, March, and mi in 三つ mittsu, three things. The reading depends on the word, never on the character, so a learner meets each combination as a vocabulary item of its own.

Why four is yon, seven nana and nine kyū

Three numbers have two Sino-Japanese readings, and everyday Japanese prefers one of them for reasons of sound. Four is mostly yon, because shi is also the reading of 死, death. Nine is mostly kyū, because ku sounds like 苦, suffering. Seven is mostly nana, a native form, because shichi is easily confused with ichi, shi and hachi.

The older forms have not disappeared. They live in fixed words: April is 四月 shigatsu, July 七月 shichigatsu, September 九月 kugatsu, as the months in Japanese show. The English Wikipedia article on Japanese numerals adds that shi and shichi are still preferred in some set words and when counting off a sequence, so ichi, ni, san, shi … is heard as well.

Building bigger numbers in Japanese

From eleven upwards the numbers in Japanese are built like a sum, largest unit first. 十一 jūichi is ten-one, eleven; 二十 nijū is two-ten, twenty; 九十九 kyūjūkyū is ninety-nine. Hundreds and thousands follow the same logic with 百 hyaku and 千 sen. One hundred is plain 百, without a one in front, and one thousand is plain 千.

Some combinations change their sound. Three hundred is sanbyaku, six hundred roppyaku and eight hundred happyaku; three thousand is sanzen and eight thousand hassen. These are listed in the article on Japanese numerals and have to be learned, since nothing in the kanji 三百 or 八千 shows them.

The real difference from English begins at ten thousand. English groups digits by thousands, Japanese by myriads of four digits: 万 man is 10,000, 億 oku is 100,000,000 and 兆 chō is a million million. Ten thousand needs a leading one, 一万 ichiman. A million is therefore 百万 hyakuman, a hundred ten-thousands, and a figure such as 2,036,521,801 is read in blocks of four: 20 億 3652 万 1801. Anyone converting large numbers between English and Japanese has to move the comma in their head.

Arabic digits are the more common choice in horizontal text and kanji numerals in vertical text, according to the article on Japanese numerals. Set words such as 一人 hitori, one person, keep the kanji in either direction.

Counters: how numbers attach to things

A Japanese number rarely stands directly before a noun. It takes a counter word, 助数詞 josūshi, chosen by the shape or kind of the thing counted. 人 nin counts people, 枚 mai flat things such as paper, plates and shirts, 本 hon long thin things such as pens, bottles and rivers, and 匹 hiki small animals and fish. つ, the general counter of the native set, covers everything else up to ten.

Counters bring their own sound changes. One person is 一人 hitori and two people 二人 futari, both native forms, while four people is 四人 yonin. With 本 the number and the counter merge: 一本 ippon, 三本 sanbon, 六本 roppon. The English Wikipedia article on Japanese counter words lists these forms; the months page shows another counter, ヶ月 kagetsu, used for lengths of time.

Order uses the suffix 番目 banme: 二番目 nibanme is the second in a row. Wiktionary's example is K2, 世界で二番目に高い山, the second-highest mountain in the world.

Formal numerals: 壱, 弐, 参 and 拾

Japanese documents that record sums of money use special forms, 大字 daiji, for some numbers, as the English Wikipedia article on Japanese numerals describes. The simple strokes of 一, 二 and 三 could be turned into higher numbers with a pen, so such documents write 壱 for one, 弐 for two, 参 for three and 拾 for ten, forms that resist alteration.

Banknotes carry the same habit. According to the English Wikipedia article on Japanese numerals, the yen notes print their values as 千, 弐千, 五千 and 壱万. The daiji are read exactly like the ordinary numerals; only the shape changes.