Tôi tra mã bưu chính.

Here, tra means to look up or to check in a reference source, such as a list, book, or website.

So tra mã bưu chính means to look up a postal code.

A very common fuller form is tra cứu, so you may also hear:

• Tôi tra cứu mã bưu chính.

That often sounds a bit more natural in everyday use.

Because Vietnamese does not translate English phrasal verbs piece by piece.

In English, look up is a two-word verb. In Vietnamese, that idea is expressed by a single verb or fixed expression such as tra or tra cứu.

So you should learn:

• tra mã bưu chính = look up a postal code

not:

• look = one word
• up = another word

It breaks down like this:

• mã = code
• bưu chính = postal / mail service

So mã bưu chính literally means postal code.

Depending on the speaker and context, you may also hear:

• mã bưu điện
• mã ZIP

But mã bưu chính is a correct standard term.

Yes, in this sentence it is very similar.

Vietnamese here follows:

• Tôi = I
• tra = look up
• mã bưu chính = postal code

So the pattern is:

• Subject + Verb + Object

That is the same basic order as English:

• I look up the postal code.

Vietnamese usually does not use articles like a, an, or the.

So mã bưu chính can mean:

• a postal code
• the postal code
• postal codes in a general sense

The exact meaning depends on context.

If you want to be more specific, Vietnamese can add other words:

• một mã bưu chính = a postal code
• mã bưu chính này = this postal code
• mã bưu chính đó = that postal code

It can mean either, depending on context.

Vietnamese often does not mark tense or aspect as explicitly as English does. So Tôi tra mã bưu chính can be understood as:

• I look up postal codes
• I am looking up a postal code

If you want to make the ongoing action clearer, you can say:

• Tôi đang tra mã bưu chính.

Here, đang shows that the action is in progress.

Tôi is a neutral and safe way to say I. It is very common in standard Vietnamese, writing, and polite speech.

However, Vietnamese pronouns depend a lot on relationship, age, and social situation. In real conversations, people often use other words for I, such as:

• em
• anh
• chị
• mình

So tôi is correct, but it is not the only possible choice.

Yes, it is grammatical and understandable.

However, many speakers would more naturally say:

• Tôi tra cứu mã bưu chính.

That version sounds a bit more complete and idiomatic.

If you mean the action is happening right now, a very natural sentence is:

• Tôi đang tra cứu mã bưu chính.

So your original sentence is fine, but there are slightly more common alternatives.

No, you do not.

In Tôi tra mã bưu chính, mã bưu chính can directly follow the verb as the object. No classifier is needed.

Vietnamese classifiers are more relevant in expressions with numbers, demonstratives, or certain noun types. But here, mã itself is already a noun meaning code, so the phrase works naturally without any extra classifier.

A rough pronunciation guide is:

• Tôi: roughly like toy
• tra: roughly trah
• mã: roughly ma, but with the ngã tone
• bưu: roughly byoo
• chính: roughly cheeng, with a rising tone

The tones are:

• tôi: level tone
• tra: level tone
• mã: ngã tone
• bưu: level tone
• chính: sắc tone

For learners, the hardest part is usually getting the tones right, especially on mã and chính.