# What is the correct syntax for large numbers in kanji?

Say I was trying to write the number 3,476,521,893,421 in kanji. How would I go about this? My guess was 三万四千七百六十五億二千百八十九万三千四百二十一 but it looks really wrong to me because it feels too Western to be correct.

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In what way does it feel 'too Western'? – Sjiveru Aug 19 '14 at 5:24
The whole grouping thing, where I group all of "三万四千七百六十五" under 億. I'm just kind of worried that it might be misconstrued as something else. – Kelyn Ferguson Aug 19 '14 at 5:28
That's how it works, though - you can have 三十億 just as much as you can have 三十万, and it iterates upwards. You do have one mistake here, but that's just having ()万億, which isn't possible - each time you iterate, you replace the 万 slot with the next highest level. – Sjiveru Aug 19 '14 at 5:31
Ooh okay, thank you. So I would replace the first 万 character with 兆 and it should all be correct? – Kelyn Ferguson Aug 19 '14 at 5:37

The counting system for large numbers is almost the same as Western numbers, except that digits are delimited into blocks of four instead of three. You add "thousand, million, billion, trillion, ..." for each 3 digit, and in Japanese, we add "万, 億, 兆, 京【けい】, ..." for each 4 digit.

The "correct" format to write long numbers depends on the situation.

1. 三兆四千七百六十五億二千百八十九万三千四百二十一

This is the most basic form based on the pronunciation, but too lengthy and less readable. This is on math textbooks for young students, but I think this is generally avoided after we graduate from junior high school.

It's almost like saying in English, "three trillion and four hundred seventy six billion and five hundred twenty one million and eight hundred ninety three thousand and four hundred twenty one". --- Can you understand this instantly?

2. 三兆四七六五億二一八九万三四二一
三兆四七〇五億二一八〇万三四二一 (= 3,470,521,803,421)

Leave 4-digit grouping unit (万、億、兆、...) and omit 十、百、千. Use 漢数字ゼロ(〇) to represent zero. This preserves both readability and brevity, so this is the preferred style in newspapers. If you don't mind using some Arabic numbers and you are writing horizontally, you can do like this:

3兆4765億2189万3421

Actually this is the most understandable way (even easier than "3,476,521,893,421") for Japanese.

3. 三四七六五二一八九三四二一
三四七〇五二一八〇三四二一 (= 3,470,521,803,421)

Simply replace Arabic numerals with kanji numerals (again, use 〇 for zero). This is typically used for phone numbers, address, etc., but less readable for generic big integers.

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