Counting 1-10 should be easy, right?
“Ichi, ni, san, yon... (or is it shi?), go, roku, nana (or shichi), hachi, kyuu (but sometimes ku)...”
Oh, yeah...Japanese has multiple words for the same number! Seven can be either "nana" or "shichi", for example.
So how do you know which word to use?
Sometimes, either is fine – like when you count 1-10, for example. But sometimes, only one word will do.
Let's take a look at some of those special cases.
FOUR - yon / shichi / yo
Yon is used in ages:
よんさい yonsai four years old
and in big numbers:
よんじゅう yonjuu 40
よんひゃく yonhyaku 400
よんせん yonsen 4,000
よんまん yonman 40,000
But you have to use shi for the month:
しがつ shigatsu April
And there’s yo, too, occasionally. Think of it as an abbreviated "yon":
よじ yoji 4 o’clock
よにん yo’nin four people
SEVEN - nana / shichi
Nana is also used in ages:
ななさい nanasai 7 years old
...and in big numbers:
ななじゅう nanajuu 70
ななひゃく nanahyaku 700
ななせん nanasen 7,000
ななまん nanaman 70,000
But shichi must be used in the month AND the o’clock:
しちがつ shichigatsu July
しちじ shichiji 7 o’clock
NINE - kyuu / ku
Nine is usually kyuu, but a notable exception is:
９時くじ kuji nine o’clock
When is a one not a one? When it’s January
So why does Japanese have multiple words for the same number?
It's partly to do with superstition - “shi” sounds like the Japanese word for death and “ku” can mean suffering; “shichi” can also mean “place of death”.
But actually, most languages have multiple words for numbers. We have this in English, too:
1st is “first” (not “one-th”)
The first month of the year is “January” (not “month one”)
Practice makes perfect
Once you've learned which number word to use when, the next step is to practice until they stick!
Anyway, I hope these examples have demystified Japanese numbers for you a little bit. How do you like to practice numbers?
This blog post started life as the answer to a question in one of my Japanese classes (back in 2015!) If you have a question you can't find the answer to, please let me know in the comments or on Facebook / Twitter.
First published November 2015
Updated November 27, 2018