かず
Ten readings, and everything else is built from them
Memorise 1–10 and you can already assemble every number up to 99.
13 = じゅうさん
4, 7 and 9 each have two readings. These three are the whole difficulty.
4 = よん / し
Japanese groups digits in fours, not threes — 10,000 is one まん.
100,000 = じゅうまん
いち、に、さん… よん？ し？
Both are right. よん is the safer default — I'll show you when to use し.
いち 〜 じゅう
This is the only part you have to learn by heart. 🔊 Tap any row to hear it. Three of them — 4, 7 and 9 — have two readings, and both are correct.
Default to よん・なな・きゅう when you are just saying a number out loud — they are clearer, and nobody will think you said something else. し・しち・く aren't optional extras, though — they are locked into certain phrases, and you meet the first one in the very next unit: four people is よにん, never よんにん. Clock times and dates are the other place they live. Counting down from ten, for example, everyone says …さん、に、いち.
じゅういち 〜 きゅうじゅうきゅう
There are no new words here — you place the ten you already know. The only thing to get right is the order: what comes before じゅう multiplies it, what comes after adds to it.
48 is 4 ×10, then 8 → よんじゅうはち. You read it left to right, exactly as the digits are written. There is no Japanese equivalent of “forty-eight” as a single new word.
ひゃく・せん・まん
Same assembly, one wrinkle: five combinations change their sound because the plain version is awkward to say. They are coloured below — those five are worth memorising as whole words. Notice also that 100 and 1,000 take nothing in front, unlike English “one hundred”.
English commas group digits in threes — thousand, million, billion. Japanese groups them in fours — まん, おく. So 10,000 is not “ten thousand” but いちまん, one まん. That mismatch is the whole reason big numbers feel slow at first: you are not translating, you are regrouping. Above ten thousand, find the まん first, then read what is left.
ドリル
Say it out loud before you tap. The deck leans on the sound changes and the two-reading numbers, because the easy rows stick after one read of the table.
Card 1 / 16
クイズ
Twelve numbers. Every wrong choice is a real mis-assembly — right pieces, wrong sound change, or right sounds in the wrong order.
Question 1 / 12 · 0 correct