Basic numbering in Japanese
There are two ways of writing the numbers in Japanese, in Arabic numerals (1, 2, 3) or in Chinese numerals (一, ニ, 三). The Arabic numerals are more often used in horizontal writing, and the Chinese numerals are more common in vertical writing.
(Some numbers have multiple names.)
|Number||Character||Preferred reading||On reading / 音読み||Kun reading / 訓読み|
|0||零／〇||zero||rei / れい||(none)|
|1||一||ichi||ichi, itsu / いち、いつ||hito (abbrev. hi) / ひと(つ)|
|2||二||ni||ni, ji / に、じ||futa (abbrev. fu) / ふた(つ)|
|3||三||san||san / さん||mi / みっ(つ)|
|4||四||yon||shi / し||yo / よっ(つ)|
|5||五||go||go / ご||itsu / いつ(つ)|
|6||六||roku||roku, riku / ろく、りく||mu / むっ(つ)|
|7||七||nana||shichi, shitsu / しち、しつ||nana / なな(つ)|
|8||八||hachi||hachi, hatsu / はち、はつ||ya / や(つ)、や(っつ)|
|9||九||kyū||kyū, ku / きゅう、く||kokono / ここの(つ)|
|10||十||jū||jū / じゅう||tō / とお|
|100||百||hyaku||hyaku / ひゃく||(momo / もも)|
|1,000||千||sen||sen / せん||(chi / ち)|
|10,000||万||man||man, ban / まん、ばん||(yorozu / よろず)|
|8,000,000||八百万||happyakuman||happyakuman||(yaoyorozu* / やおよろず)|
The numbers 4 and 9 are considered unlucky in Japanese: 4, pronounced shi, is a homophone for "death"; 9, when pronounced ku, is a homophone for "suffering." The number 13 is also considered unlucky, though this is a carryover from Western tradition.
In modern Japanese, the kun readings are only used for single digit numbers and day-of-month names, although in many contexts the on readings will be used instead. Intermediate numbers are made by combining these elements:
Tens from 20 to 90 are "(digit)-jū".
Hundreds from 200 to 900 are "(digit)-hyaku".
Thousands from 2000 to 9000 are "(digit)-sen".
There are some phonetic modifications to larger numbers, but they are a minor detail.
In large numbers, elements are combined from largest to smallest, and zeros are implied.
|百五十一||151||hyaku go-jū ichi|
|四百六十九||469||yon-hyaku roku-jū kyū|
|二千二十五||2025||ni-sen ni-jū go|
Powers of 10
Following Chinese tradition, large numbers are created by grouping digits in myriads (every 10,000) rather than the Western thousands (1000):
Examples: (spacing by groups of four digits is given only for clarity of explanation)
1`0000 : 一万 : ichi-man
983`6703 : 九百八十三万六千七百三 : kyū-hyaku hachi-jū san man, roku-sen nana-hyaku san
20`3652`1801 : 二十億三千六百五十二万千八百一 : ni-jū oku, san-zen rop-pyaku go-jū ni-man, sen hap-pyaku ichi
However, numbers written in Arabic numerals are separated by commas every three digits following Western convention.
In Japanese, when long numbers are written out in kanji, zeros are omitted for all powers of ten. Hence 302 is 三百二. In contrast, Chinese requires the use of 零 wherever a zero appears, e.g. 三百零二 for 302.
Japanese has two systems of numerals for decimal fractions. They are no longer in general use, but are still used in some instances such as batting and fielding averages of baseball players, winning percentages for sports teams, and in some idiomatic phrases (such as 五分五分の勝負 "fifty-fifty chance"), and when representing a rate or discount.
One system is as follows:
|Japanese name (romaji)||Japanese name (kanji)||Fraction|
|bu||分||one tenth; 10-1|
|rin||厘||one hundredth; 10-2|
|mō||毛||one thousandth; 10-3|
The other system of representing these decimal fractions of rate or discount uses a system "shifted down" with a bu becoming a "one hundredth" and so on, and the unit for "tenth" becoming wari:
This is often used with prices. For example:
一割五分引き ichi-wari go-bu biki "15% discount"
打率三割八分九厘 daritsu san-wari hachi-bu kyū-rin "batting average .389"
With the exception of wari, these are rarely seen in modern usage. Decimal fractions are typically written with either kanji numerals (vertically) or Arabic numerals (horizontally), preceded by a decimal point, and are read as successive digits, as in Western convention. Note that they can be combined with either the traditional system of expressing numerals (42.195 kilometers: 四十二・一九五 キロメートル), in which powers of ten are written, or with the place value system, which uses zero (50.04 percent: 五〇・〇四 パーセント).
Japanese has a separate set of kanji for numerals called daiji (大字) used in legal and financial documents to prevent an unscrupulous person from adding a stroke or two, turning a one into a two or a three. These are