The numbers in Japanese both are written in kanji or arabic numerals. Kanji are the traditional Japanese way to write them, however it is very common to use arabic numbers. Some Japanese numbers have more than one way of saying them.
Which pronunciation of the number you are using, depends on what you are talking about. When you are counting for 9 you use kyuu. When you count to 10 you can use both words for 7 and 4, but after ten you use yon and nana to count.
In Japanese there numbers past ten do not use different words. Instead they follow the pattern ten + one, ten + two. To say 11, you take 10 (juu) + 1 (ichi) after it. The pattern continues.
When you get to 20 you add 2 (ni) in front of 10 (juu). In English this is equal to saying two ten. This pattern is the same for 30, 40 and so on.
To say numbers between 21-29 you follow the same pattern and add the number after juu like you did number 11-19.
This pattern continues all the way up to 99.
The word for hundred is hyaku. The same pattern applies to all numbers 100-199.
When you get to 200, you need to add two in front of hundred.
This pattern continues the same for most numbers but there are some differences in pronunciation. The numbers below don't follow the usual pattern so you have to memorize them.
300 becomes sanbyaku (さんびゃく)
600 becomes roppyaku (ろっぴゃく)
800 becomes happyaku (はっぴゃく)
When you get to 1000 you use the word sen which means thousand. You follow same pattern as before.
There are only two odd rules with numbers in the 1000's.
3000 becomes sanzen (さんぜん)
8000 becomes hassen (はっせん)
When saying 10,000 you use the counter man which is ten thousand. However the is something different. For 10,000 you must say ichi before man. This pattern continues.
We will learn to count higher in future lessons. Don't worry so much if you can't remember all these numbers, we will review numbers a lot in our lessons.