Japanese numerals

The system of Japanese numerals is the system of number names used in the Japanese language.

(Some numbers have multiple names.)

Number 0 1 2 3 4 5 6 7 8 9 10 100 1000
Character 零一二三四五六七八九十百千
Preferred reading rei ichi ni san yon go roku nana hachi kyū jū hyaku sen
On Reading rei ichi ni san shi go roku shichi hachi kyū jū hyaku sen
音読み れいいちにさんしごろくしちはちきゅうじゅうひゃくせん
Kun Reading hitotsu futatsu mittsu yottsu/yon itsutsu muttsu nanatsu/nana yattsu kokonotsu tō chi
訓読み ひとつふたつみっつよっつ／よんいつつむっつななつやっつここのつとうち

As you can see, 4 and 7 do not use their On readings, this is superstitous - 死 (death) is pronounced shi.

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.
十一 : 11 : jū-ichi
十七 : 17 : jū-nana
百五十一 : 151 : hyaku go-jū ichi
三百二 : 302 : sam-byaku-ni
四百六十九 : 469 : yon-hyaku roku-jū kyū
二千二十五 : 2025 : ni-sen ni-jū go

Now the main point: REALLY big numbers are made in a manner nearly identical to that in English, EXCEPT they use groups for four digits:

Rank 10⁴ 10⁸ 10¹²
Character 万億兆
Name man oku chō

Examples: (spacing by groups of four digits is given only for clarity of explanation)
1`0000 : ichi-man
983`6703 : kyū-hyaku hachi-jū san man roku-sen nana-hyaku san
20`3652`1801 : ni-jū oku san-zen rop-pyaku go-jū ni-man sen hap-pyaku ichi

Note that, in Japanese as well as English, the word for "zero" is not used in the name of any integer greater than zero; unlike Chinese, which requires the use of 零 wherever there is a group of zeroes, i.e. 三百零二 for 302.

Since Japanese language was heavily influenced by Chinese, Japanese numerals for small numbers are identical to Chinese numerals except the difference in pronunciations. For large numbers, the numerals are often different, because of different number syntax.