Numbers in japanese

Japanese gave up its original number system more than a thousand years ago. Modern Japanese uses this number system which was imported from Chinese. Ancient Japanese numeral system is not used these days except 1 through 10, that can be sometimes used as alternate vocabulary. From 0 to 100 the modern Japanese number system is essentially the same as the Chinese system except for the pronunciation.

Numbers	Japanese	English
	Romaji [Pronunciation]
0	rei [rei]	zero
1	iti [ichi]	one
2	ni [ni]	two
3	san [san]	three
4	si / yon* [shi / yon*]	four
5	go [go]	five
6	roku [roku]	six
7	siti / nana [shichi / nana]	seven
8	hati [hachi]	eight
9	ku / kyuu [ku / kju:]	nine
10	zyuu [ju]	ten
100	hyaku [hjaku]	one hundred
1,000	sen [sen]	one thousand
10,000	man [man]	ten thousand

* There are a few reasons for the number four and seven being different.
With 'shi' meaning death in Japanese it is preferable to use 'yon'. Also, 'shi' and 'shichi' sound very much alike so to avoid confusion, often  'yon' and 'nana' is used to differentiate on from the other.

You can see Japanese terminology used in Jiu-Jitsu by clicking here