Japanese Numbers: 0 to Trillion (Complete Guide)

Mastering numbers is one of the most basic survival skills in any country—including Japan. Picture bargaining for souvenirs in Tokyo, asking for a train platform number, or exchanging phone numbers with a new friend. Without numbers, you get stuck fast.

The good news: the Japanese number system is highly regular and logical. The catch: large units (from ten thousand up) follow a different grouping than the international three-digit system many learners know—and that trips people up.

This guide walks through everything step by step, from zero to trillion, with memory tricks along the way.

1. Basic Numbers (0 - 10)

This is the foundation you must know cold. Almost every larger number is built from these.

Unlucky numbers? 4 (Shi) and 9 (Ku) are often treated as unlucky because they sound like “death” (shinu) and “suffering” (kurushii). Hospitals or hotels sometimes skip room 4 or 9. Prefer Yon and Nana/Kyuu in everyday speech, except in set contexts (time, months, and similar).

2. Teens and Tens (11 - 99)

Japanese number logic stays simple:

• 11 is “ten one” (Juu Ichi).
• 12 is “ten two” (Juu Ni).
• 20 is “two ten” (Ni Juu).
• 99 is “nine ten nine” (Kyuu Juu Kyuu).

No irregular words like “eleven” or “twelve.” Everything is mathematical.

3. Hundreds (Hyaku) - 100 to 999

The unit for 100 is Hyaku (百). Base pattern: number + Hyaku. There are three sound-change exceptions you must memorize.

• 100: Hyaku (not Ichi-hyaku)
• 200: Ni-hyaku
• 300: San-byaku (not San-hyaku) — use B
• 400: Yon-hyaku
• 500: Go-hyaku
• 600: Roppyaku (not Roku-hyaku) — P + sokuon
• 700: Nana-hyaku
• 800: Happyaku (not Hachi-hyaku) — P + sokuon
• 900: Kyuu-hyaku

Example:

• 365 = San-byaku Roku-juu Go.

4. Thousands (Sen) - 1,000 to 9,999

The unit for 1,000 is Sen (千). Two sound exceptions appear here.

• 1,000: Sen (not Ichi-sen, except formal/money: Issen)
• 2,000: Ni-sen
• 3,000: San-zen (not San-sen) — use Z
• 4,000: Yon-sen
• 5,000: Go-sen
• 6,000: Roku-sen
• 7,000: Nana-sen
• 8,000: Hassen (not Hachi-sen) — sokuon
• 9,000: Kyuu-sen

Example:

• 2020 = Ni-sen Ni-juu.

5. Ten Thousands (Man) - The Big Cultural Shift

This is the biggest gap between Western three-digit grouping and Japanese. Western languages usually group by 3 digits (thousands, millions, billions). Japanese groups by 4 digits (Man, Oku, Chou).

After thousand (Sen), the next core unit is not a separate “ten thousand” word in the Western sense—it is Man (万).

• 10,000 = Ichiman (one Man). Not Juu-sen!
• 20,000 = Niman.
• 100,000 = Juuman (ten Man).
• 1,000,000 (one million) = Hyakuman (one hundred Man).

Fast conversion tip: For a large number, count 4 zeros from the right and split there.

• 150,000 → 15 | 0000 → Juugo-man.
• 3,500,000 (3.5 million) → 350 | 0000 → Sanbyaku-gojuu-man.

This takes practice. One million is not “one million” as a single Japanese unit—it is “one hundred Man” (Hyakuman).

6. Giant Numbers (Oku & Chou)

After four Man digits (up to 9999 Man), the next unit is Oku (億). Oku is 100 million.

• 100,000,000 (one hundred million) = Ichioku.
• 1,000,000,000 (one billion) = Juuoku (ten Oku).
• 10,000,000,000 (ten billion) = Hyakuoku.

Above Oku comes Chou (兆) for trillion.

• 1 trillion = Itchou (one Chou).

7. Counters (Josuushi)

In Japanese you cannot simply say “two apples” as “Ni Ringo.” You need a counter that matches the kind of object—similar to “two sheets of paper” or “three cups of coffee” in English, but Japanese is stricter and more systematic.

A. General counters (small/abstract items)

If you do not know a specific counter, use this native Japanese set (through 10).

1. Hitotsu (一つ)
2. Futatsu (二つ)
3. Mittsu (三つ)
4. Yottsu (四つ)
5. Itsutsu (五つ)
6. Muttsu (六つ)
7. Nanatsu (七つ)
8. Yattsu (八つ)
9. Kokonotsu (九つ)
10. Too (十)

• Question: “How many?” = Ikutsu (幾つ).
• Example: “Ringo o futatsu kudasai” (Two apples, please).

B. Specific counters (must-know)

• -mai (枚): flat thin things (paper, shirts, plates, sliced bread).
  • Ichimai, Nimai, Sanmai.
• -dai (台): machines & vehicles (cars, computers, bikes).
  • Ichidai, Nidai, Sandai.
• -hon/bon/pon (本): long cylindrical things (pens, bottles, umbrellas, trees, legs).
  • Ippon, Nihon, Sanbon. (Watch the sound changes!)
• -nin (人): people.
  • Exceptions: 1 person = Hitori, 2 people = Futari.
  • 3+ = Sannin, Yonin, and so on.

8. Practice problems

Convert these into Japanese:

1. 45
2. 365
3. 1,500
4. 15,000
5. Three people

9. Prices and money (Okane)

Japan’s currency unit is Yen (円), read En. Read the number as usual, then add “en.”

• 100 Yen = Hyaku-en.
• 1,500 Yen = Sen Go-hyaku en.
• 10,000 Yen = Ichiman-en. (Remember: not Juu-sen en).

For Indonesian rupiah amounts (common on this site), katakana Rupia (ルピア) is used.

• 100,000 rupiah = Juuman Rupia.

10. Fractions and decimals

How do you say “half” or “point”?

A. Decimals (point)

Japanese (and international English) use a decimal point (.). The point is read Ten (点).

• 1.5 = Ichi ten Go.
• 3.14 = San ten Ichi Yon.
• 0.5 = Rei ten Go.

B. Fractions

The order is the reverse of many European languages’ “numerator over denominator” wording: Japanese is [bottom] bun no [top] (“X parts, of which Y”).

Formula: [denominator] bun no [numerator]

• 1/2 (half) = Ni bun no Ichi.
• 1/3 (one third) = San bun no Ichi.
• 3/4 (three quarters) = Yon bun no San.

11. Math operations

Simple school arithmetic terms:

• Plus (+) = Tasu (足す).
  • 1 + 1 = 2 (Ichi tasu Ichi wa Ni).
• Minus (-) = Hiku (引く).
  • 5 - 2 = 3 (Go hiku Ni wa San).
• Times (×) = Kakeru (掛ける).
  • 2 × 3 = 6 (Ni kakeru San wa Roku).
• Divided by (÷) = Waru (割る).
  • 10 / 2 = 5 (Juu waru Ni wa Go).
• Equals (=) = Wa (は) or Ikooru (イコール).

Practice: Check Your Understanding

Q1: How do you say 4,500 in Japanese?

Answer: 四千五百よんせんごひゃく (Yon-sen go-hyaku)

Q2: How do you say 30,000 (thirty thousand)?

Answer: 三万さんまん (San-man) — Japanese uses the Man unit (10,000), so 30,000 = 3 × Man.

Q3: Name three numbers with special sound changes in the hundreds (hyaku)!

Answer: 300 (San-byaku, not San-hyaku), 600 (Roppyaku, not Roku-hyaku), 800 (Happyaku, not Hachi-hyaku).

Conclusion

The Japanese number system is highly systematic. The biggest challenges are getting used to the Man unit (10,000) and memorizing sound changes (300, 600, 800, 3000, 8000).

Key points to remember:

• Numbers 1–10 are the foundation—know them well.
• Hyaku (100) has 3 sound exceptions: 300, 600, 800.
• Sen (1000) has 2 sound exceptions: 3000, 8000.
• Japanese groups large numbers by 4 digits (Man, Oku, Chou), not by 3.
• Josuushi (counters) are required when counting objects.

Success comes from practice. Try reading license plates or supermarket prices in Japanese.

Related reading:

• Time and the clock
• Dates and days

頑張がんばって！ (Ganbatte / Keep going!)

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