Japanese numbers from 1 to 100

One to ten

Learn these ten first. Three of them have two readings.

きゅう and じゅう carry long vowels — kyū and jū, held for an extra beat, not "kyu" and "ju".

Eleven to ninety-nine is just assembly

Above ten, numbers are built rather than memorized. Everything hangs off じゅう (10).

For the teens, put the ones digit after じゅう: 11 is じゅういち, 15 is じゅうご.

For the tens, put the multiplier in front: 20 is にじゅう, 30 is さんじゅう, 90 is きゅうじゅう.

Combine the two and you are finished: 25 is にじゅうご, 78 is ななじゅうはち.

It reads exactly as "two-ten-five" — the same logic as Chinese and Korean numerals. There is no new rule to learn.

When to use which reading for 4, 7 and 9

As a beginner, default to よん, なな and きゅう. They are much safer.

し (4) sounds like 死 (death) and く (9) like 苦 (suffering), so both are avoided in everyday speech. It is why some Japanese buildings skip room 4.

But fixed expressions kept the older readings. July is しちがつ, April is しがつ, September is くがつ. Times too: 4 o’clock is よじ, 7 is しちじ, 9 is くじ.

Hundreds and thousands

100 is ひゃく and 1000 is せん. A few positions change sound.

300 is not さんひゃく but さんびゃく; 600 is ろっぴゃく and 800 is はっぴゃく. The shift is purely for ease of pronunciation.

On the thousand side, 3000 becomes さんぜん and 8000 becomes はっせん.

Rather than memorizing, say them out loud. さんびゃく is obviously easier to produce than さんひゃく, and that is the whole reason.

Reading phone numbers

Phone numbers are read digit by digit, and the hyphen is read as の (no). 03-1234-5678 becomes "zero-san no ichi-nī-san-yon no gō-roku-nana-hachi".

Two things change. Zero is read ゼロ or れい, and 2 and 5 are stretched: に becomes にー and ご becomes ごー.

The stretching keeps them distinct. に is short enough to be missed, and ご shares its opening with ろく. This lengthening is specific to reading out digits.