Two Number Systems
Japanese uses two distinct number systems with different origins and uses:
| System | Origin | Japanese Term | Range | Usage |
|---|---|---|---|---|
| Native | Japanese | 和語 (わご) | 1-10 | General items, traditional |
| Sino | Chinese | 漢語 (かんご) | All numbers | Most counting, modern use |
Native: ひとつ、ふたつ、みっつ
Sino: いち、に、さん
Complete Comparison (1-10)
| # | Native Reading | Kanji | Sino Reading | Kanji |
|---|---|---|---|---|
| 1 | ひとつ (hitotsu) | 一つ | いち (ichi) | 一 |
| 2 | ふたつ (futatsu) | 二つ | に (ni) | 二 |
| 3 | みっつ (mittsu) | 三つ | さん (san) | 三 |
| 4 | よっつ (yottsu) | 四つ | よん/し (yon/shi) | 四 |
| 5 | いつつ (itsutsu) | 五つ | ご (go) | 五 |
| 6 | むっつ (muttsu) | 六つ | ろく (roku) | 六 |
| 7 | ななつ (nanatsu) | 七つ | なな/しち (nana/shichi) | 七 |
| 8 | やっつ (yattsu) | 八つ | はち (hachi) | 八 |
| 9 | ここのつ (kokonotsu) | 九つ | きゅう/く (kyuu/ku) | 九 |
| 10 | とお (too) | 十 | じゅう (juu) | 十 |
Key Observations
- Native numbers end in つ (tsu) for 1-9
- Native number 10 is とお (too), not とおつ
- Native numbers are rarely used above 10
- Sino numbers continue infinitely
When to Use Native Numbers
1. With General Counter つ
When counting general items without specific counters:
りんごを3つ買いました
"I bought 3 apples"
質問が2つあります
"I have 2 questions"
問題は4つです
"There are 4 problems"
2. Young Children's Age
Informally, for children under 10:
A: いくつ？
"How old?"
B: 5つ
"Five (years old)"
More formally: 5 歳 (ごさい)
3. Time Expressions
For counting hours (but NOT telling time):
2時間 = ふたつ分 (informal)
But saying the time: 2時 (にじ) - uses Sino
4. Traditional or Poetic Contexts
一つ二つと星が見える
"One by one, stars appear"
七つの海
"The seven seas"
5. Set Phrases and Idioms
一つよろしく
"Please take care of it"
二つ返事
"Immediate reply"
三つ子の魂百まで
"The soul of a three-year-old lasts until 100" (proverb)
When to Use Sino Numbers
1. With Specific Counters
All specific counters use Sino numbers:
3人 (さんにん) - 3 people
2本 (にほん) - 2 long objects
5枚 (ごまい) - 5 flat objects
4匹 (よんひき) - 4 small animals
2. Money
100円 (ひゃくえん) - 100 yen
1,000円 (せんえん) - 1,000 yen
50円 (ごじゅうえん) - 50 yen
3. Time (Clock Time)
3時 (さんじ) - 3 o'clock
5分 (ごふん) - 5 minutes
2時間 (にじかん) - 2 hours
4. Dates and Calendar
1月 (いちがつ) - January
5日 (いつか) - 5th day
2025年 (にせんにじゅうごねん) - 2025
Exception: Days 1-10 have special readings, but they're still based on Sino system.
5. Mathematical Operations
1 + 2 = 3
いち たす に は さん
5 - 3 = 2
ご ひく さん は に
6. Phone Numbers and Addresses
電話: 090-1234-5678
ゼロきゅうゼロ の いちにさんよん の ごろくななはち
住所: 東京都渋谷区1-2-3
とうきょうと しぶやく いちのにのさん
7. Age (Formal)
25歳 (にじゅうごさい) - 25 years old
30歳 (さんじゅっさい) - 30 years old
Exception: 20 歳 is はたち (special word)
8. Numbers Above 10
Always use Sino numbers:
15 = じゅうご (not じゅうごつ)
20 = にじゅう
100 = ひゃく
1,000 = せん
Common Patterns
Native Numbers Pattern
Stem + つ for 1-9:
ひと + つ = ひとつ (1)
ふた + つ = ふたつ (2)
み + つ = みっつ (3)
よ/よっ + つ = よっつ (4)
いつ + つ = いつつ (5)
む + つ = むっつ (6)
なな + つ = ななつ (7)
や + つ = やっつ (8)
ここの + つ = ここのつ (9)
とお (10) - no つ!
Sino Numbers with Counters
Number + Counter:
1 + 人 = ひとり (exception!)
2 + 人 = ふたり (exception!)
3 + 人 = さんにん
4 + 本 = よんほん
5 + 枚 = ごまい
Historical Context
Origin of Native Numbers
- Ancient Japanese words
- Existed before Chinese influence
- Limited to basic counting
- Still used in daily conversation
Origin of Sino Numbers
- Imported from China around 5th-6th century
- Came with Chinese writing system
- More systematic and expandable
- Became standard for most counting
Special Cases and Exceptions
Numbers with Two Systems
Some numbers can use either system depending on context:
Age (informal): 5つ (いつつ)
Age (formal): 5歳 (ごさい)
General items: 3つ (みっつ)
With counter: 3個 (さんこ)
20 Years Old: はたち
A special native word:
20歳 = はたち
Not: にじゅっさい ❌ (though sometimes used)
Days of the Month (1-10)
Special readings mixing both systems:
1日 = ついたち (native origin)
2日 = ふつか (native)
3日 = みっか (native)
4日 = よっか (native)
5日 = いつか (native)
6日 = むいか (native)
7日 = なのか (native)
8日 = ようか (native)
9日 = ここのか (native)
10日 = とおか (native)
But 11 日 onwards use Sino: 11 日 (じゅういちにち)
Mixing Systems (Generally Avoided)
Don't mix systems in the same phrase:
Wrong: ふたつ人 ❌
Right: ふたり or 2人 ✓
"Two people"
Wrong: さんつ ❌
Right: みっつ or 3つ ✓
"Three (things)"
Common Conversations
Example 1: Shopping
A: りんごをいくつ買いますか？
"How many apples will you buy?"
B: 3つください
"Three, please"
A: 全部で300円です
"That's 300 yen in total"
(uses Sino for money)
Example 2: Age
A: お子さんはいくつですか？
"How old is your child?"
B: 4つです
"Four (years old)" (casual)
Or: 4歳です
"Four years old" (more formal)
Example 3: Counting Objects
A: ペンは何本ありますか？
"How many pens are there?"
(uses Sino with counter)
B: 5本あります
"There are 5"
Memory Tips
For Native Numbers
Think of them as "traditional Japanese counting":
- Used for general, everyday items
- Limited range (1-10)
- Ends in つ sound (except 10)
- More casual, conversational feel
For Sino Numbers
Think of them as "formal, systematic counting":
- Used with specific counters
- Unlimited range
- More analytical, precise
- Standard for modern contexts
Sound Changes with Counters
Sino Numbers + Counters Often Change
1 + 人 = ひとり (not いちにん)
3 + 本 = さんぼん (not さんほん)
6 + 匹 = ろっぴき (not ろくひき)
8 + 枚 = はちまい (sound lengthens)
Native Numbers Don't Use Counters
Native numbers use つ, which is already a counter:
3つ ✓ (complete)
Not: 3つ個 ❌ (redundant)
Practice Examples
Use Native Numbers
いくつありますか？
"How many are there?"
→ 5つあります
子供が何人いますか？(age)
"How many children do you have?"
→ 3つと5つです (informal age)
Use Sino Numbers
何人いますか？(people count)
"How many people are there?"
→ 5人います (ごにん)
いくらですか？
"How much is it?"
→ 500円です (ごひゃくえん)
何時ですか？
"What time is it?"
→ 3時です (さんじ)
Summary Table
| Context | System | Example |
|---|---|---|
| General items | Native | 3 つ (mittsu) |
| With counters | Sino | 3 人 (san-nin) |
| Money | Sino | 300 円 (san-byaku en) |
| Time | Sino | 3 時 (san-ji) |
| Child's age (casual) | Native | 3 つ (mittsu) |
| Age (formal) | Sino | 3 歳 (san-sai) |
| Dates | Sino | 3 月 (san-gatsu) |
| Phone numbers | Sino | 3 (san) |
| Above 10 | Sino | 15 (juu-go) |
Common Mistakes
Mistake 1: Using native numbers with counters
Wrong: みっつ人 ❌
Right: 3人 (さんにん) ✓
"Three people"
Mistake 2: Using sino numbers without counters for things
Unnatural: さん ⚠️ (when counting items)
Better: 3つ (みっつ) ✓
"Three (things)"
Mistake 3: Native numbers above 10
Wrong: じゅうつ ❌
Right: じゅう or 10個 ✓
"Ten"
Mistake 4: Wrong age expression
Too casual (adult): 25つです ❌
Correct: 25歳です (にじゅうごさい) ✓
"I'm 25 years old"
Related Grammar Points
- Number System Overview - Complete number guide
- Counter System Basics - How counters work
- General Counter (つ) - Native counting
- いくつ (ikutsu) - How many/old
- Specific Counters - 人、本、枚、etc.
- Age expressions - Talking about age
- Time expressions - Telling time
- Date expressions - Calendar dates