Japanese numerals

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

(Some numbers have multiple names. Here, I give no more than one name for a number.)

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

Name

rei

ichi

ni

san

yon

go

roku

nana

hachi

kyuu

juu

hyaku

sen

Intermediate numbers are made by combining these elements:
Tens from 20 to 90 are "(digit)-juu".
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.
11 = juu-ichi
17 = juu-nana
151 = hyaku-go-juu-ichi
302 = sam-byaku-ni
469 = yon-hyaku-roku-juu-kyuu
2025 = ni-sen-ni-juu-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	chou

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

Note that, in Japanese as well as English, the word for "zero" isn't used in the name of any integer greater than zero.

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.