Ordinal and Conventional Numbering in Chinese
序数表示法
Mandarin marks explicit ordinal rank with 第 before a number, as in 第一 or 第七. It also uses bare numbers conventionally to identify floors, building numbers, room numbers, and transport routes, where the number functions as a label rather than a count. The noun and number order is fixed by the labeling convention, and 二 follows 第 rather than 两.
Published August 15, 2026
Reviewed August 15, 2026
01 / PATTERN
See the Structure
MODEL
第 + Number; Number + Floor/Level/Building/Room/Route
Read the structure
Mandarin marks explicit ordinal rank with 第 before a number, as in 第一 or 第七. It also uses bare numbers conventionally to identify floors, building numbers, room numbers, and transport routes, where the number functions as a label rather than a count. The noun and number order is fixed by the labeling convention, and 二 follows 第 rather than 两. Keep the model 第 + Number; Number + Floor/Level/Building/Room/Route visible while you compare each sentence.
她得了第一名。
She won first place.
Choose the right context
Put 第 directly before a number to state rank or order. Use a bare number before 楼 or 层 to identify a floor or level. Use conventional label order in 13号楼, 205房间, and 302路公交车.
教室在三楼。
The classroom is on the third floor.
Respect the boundary
Do not use 两 immediately after 第 in an ordinal. Do not reverse a conventional label noun and its number marker. Do not add 第 automatically to every room, route, or building label.
她住在第两层。
(She lives on the second floor.)
Repair the pattern
两 follows the ordinal prefix: Ordinals use 第加二, so 两 cannot immediately follow 第. The building label is reversed: A building label places the number before 号楼 as one conventional unit.
她住在第二层。
Use the repaired structure without changing the intended meaning.
02 / MAP
Read the Sentence
Read from left to right and notice the job performed by each part. The labels describe this example; they are not a rule that every Chinese sentence must copy.
她得了第一名。
She won first place.
她
第
This part occupies the 第 position in the model pattern.
得了
Number; Number
This part occupies the Number; Number position in the model pattern.
第一
Floor/Level/Building/Room/Route
This part occupies the Floor/Level/Building/Room/Route position in the model pattern.
名
第
This part occupies the 第 position in the model pattern.
03 / EXAMPLES
Examples You Can Reuse
Keep the structure stable while changing the people, objects, times, or conditions. Pinyin is shown as reading support; use the Chinese sentence and translation to confirm the grammar relationship.
她得了第一名。
She won first place.
教室在三楼。
The classroom is on the third floor.
我住在13号楼。
I live in Building 13.
请坐302路公交车。
Please take bus route 302.
04 / LIMITS
When to Use It — and When Not To
Use it when
- Put 第 directly before a number to state rank or order.
- Use a bare number before 楼 or 层 to identify a floor or level.
- Use conventional label order in 13号楼, 205房间, and 302路公交车.
Do not use it when
- Do not use 两 immediately after 第 in an ordinal.
- Do not reverse a conventional label noun and its number marker.
- Do not add 第 automatically to every room, route, or building label.
05 / REPAIR
Compare Right and Wrong
Compare the smallest meaningful change. Each explanation identifies a placement, scope, form, or clause relationship instead of treating the whole sentence as one undifferentiated mistake.
她住在第两层。
她住在第二层。
两 follows the ordinal prefix
Ordinals use 第加二, so 两 cannot immediately follow 第.
我住在十三楼号。
我住在13号楼。
The building label is reversed
A building label places the number before 号楼 as one conventional unit.
她住在第两层。
Ordinals use 第加二, so 两 cannot immediately follow 第.
我住在十三楼号。
A building label places the number before 号楼 as one conventional unit.
06 / PRACTICE
Practice the Grammar Point
Complete three short tasks in order: judge the pattern, repair a common error, and build the sentence. Feedback is fixed and reviewed, so these activities do not use a checker allowance.
1. Judge the sentence
2. Choose the correction
3. Build the sentence
Build a complete sentence with 序数表示法.
07 / APPLY
Apply It in Your Sentence
Write one original sentence with 序数表示法. Your draft moves to the checker through this browser session, selects this grammar point as the first review focus, and waits for you to submit.
08 / QUESTIONS
Ordinal and Conventional Numbering Questions
Why is it 第二 rather than 第两?
Ordinal 第 takes the numeral 二. 两 is common before classifiers in counted quantities, but it does not replace 二 in this ordinal pattern.
Why does 三楼 not contain 第?
Floor, room, route, and building labels often use bare numbers by convention. 第 explicitly marks rank, while a label identifies an item in an established sequence.
09 / SOURCES
Sources and Review Notes
These references support different parts of the lesson. GF0025-2021 supports level placement only; professional grammar works support the explanation, limits, examples, and cross-checks. Their inclusion does not imply endorsement.
Chinese Proficiency Grading Standards for International Chinese Language Education (GF0025-2021)
Ministry of Education and State Language Commission · Ministry of Education of the PRC · 2021
Locator: Appendix A, Level 2 item 【二72】, PDF p. 196 (printed p. 190)
Places 第 ordinals and bare floor, building, room, and bus-route numbering at Level 2.
Official sourceTaiwan MOE Concised Mandarin Chinese Dictionary: Ordinal Numbers
Ministry of Education, Taiwan · Ministry of Education, Taiwan · 2021
Locator: Dictionary entry for ordinal numbers, definition and three expression types
Confirms 第 plus cardinal number, direct number before classifier or noun, and conventional forms as Mandarin ordinal strategies.
Official source10 / CONTINUE
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