Ordinal Numbers
序数表示法
Form ordinal numbers with 第 and understand when 第 is omitted in floors, buildings, and routes
Add 第 before a number to make it ordinal: 第一 (first), 第二 (second), etc. However, for floors, building numbers, room numbers, and bus routes, 第 is typically omitted.
The rule is simple: 第 + number = ordinal. But in daily life, floors (三楼), layers (二层), building numbers (13号楼), room numbers (205房间), and bus routes (302路) drop the 第.
Lesson Targets
Podcast
Podcast: Ordinal Numbers (序数表示法)
Listen to Jason & Amy explain the 序数表示法 pattern
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Understanding 序数表示法
Ordinal numbers in Chinese are refreshingly simple — just add 第 before any number and you have an ordinal. 第一 is "first," 第三 is "third," 第一百 is "one hundredth." No irregular forms like English ("first, second, third"). However, Chinese has a practical shortcut: in many real-life contexts like buildings, rooms, floors, and bus routes, people drop the 第 entirely. Nobody says 第三楼 — they say 三楼 (third floor). Nobody says 第302路公交车 — they say 302路公交车 (Bus 302). This is because these are more like labels than rankings. Think of it this way: when 第 is used, you are ranking things (first place, second time). When 第 is dropped, you are labeling things (Floor 3, Room 205, Building 13).
Key Points
- 第 (dì) + number = ordinal: 第一 (first), 第二 (second), 第三 (third), etc.
- 第 is used for rankings and sequences: 第一名 (first place), 第二次 (second time).
- Floors: 三楼 (3rd floor) — no 第.
- Layers: 二层 (2nd level) — no 第.
- Building numbers: 13号楼 (Building 13) — no 第.
- Room numbers: 205房间 (Room 205) — no 第.
- Bus routes: 302路公交车 (Bus 302) — no 第.
- 第 is always used with 一 in formal rankings: 第一个到的人 (the first person to arrive).
In Chinese culture, 第一 (first) carries great prestige. Students strive to be 第一名 (first place). However, the number four (四) sounds like 死 (death), so you will rarely see a "fourth floor" labeled as such in Chinese buildings — many skip from 3 to 5.
Key Vocabulary
Example Sentences
他是第一个来的。
He was the first to arrive.
这是我第三次来中国。
This is my third time coming to China.
请到三楼。
Please go to the third floor.
No 第 for floors
他住在二层。
He lives on the second level.
No 第 for layers
我住在13号楼。
I live in Building 13.
No 第 for building numbers
我的房间是205房间。
My room is Room 205.
No 第 for room numbers
你坐302路公交车。
Take Bus 302.
No 第 for bus routes
第七课讲什么？
What does Lesson 7 cover?
Common Mistakes
Floors do not use 第. Just say the number + 楼.
Bus routes do not use 第. Just say the number + 路.
For rankings, you must include 第. Without it, 一个 just means "one" not "the first."
Practice Exercises
Tips & Tricks
Simple rule: use 第 for rankings and sequences; drop 第 for addresses, floors, rooms, and bus routes.
Practice with your own address: what floor, building, and room number do you live in?
In competitions, 第一名, 第二名, 第三名 — always with 第.
When giving directions, bus routes never use 第: 你坐几路车？我坐10路。
Homework
Write a paragraph describing where you live and how to get there. Include your building number, floor, room number, and which bus to take. Then write five sentences using 第 for rankings (第一次, 第二名, etc.).