Hâlbuki siz arayacaktınız; numarayı mı kaybettiniz?

Hâlbuki means something like but, however, whereas, or even though that was the case. It introduces a contrast with what was expected before.

In this sentence, it signals an idea like:

• But you were going to call...
• However, you were supposed to call...

So it sets up a mild contradiction or surprise.

Yes. The verb ending already tells us the subject is you plural or polite singular, so siz is not strictly necessary.

• arayacaktınız already means you were going to call
• adding siz gives extra emphasis, contrast, or politeness

So siz here can sound like:

• you were the one who were going to call
• but you were supposed to call

It may also simply be there because the speaker wants to be clear or slightly emphatic.

Arayacaktınız breaks down like this:

• ara- = call / look for
• -yacak = future marker
• -tı = past
• -nız = you plural or polite singular

So literally it is a future-in-the-past form: you were going to call.

Depending on context, it can also feel like:

• you were supposed to call
• you said you would call
• you were expected to call

In this sentence, that nuance of expectation is very important.

This combination is very common in Turkish. It expresses an action that was in the future from a past point of view.

So:

• arayacaksınız = you will call
• arayacaktınız = you were going to call / you were supposed to call

English often uses forms like:

• was/were going to
• would
• was/were supposed to

So the future marker does not always mean real future time from the speaker’s present perspective. Here it shows a planned or expected action viewed from the past.

It can mean both.

• birini aramak = to call someone / to look for someone
• numarayı aramak can mean dial the number
• in this sentence, arayacaktınız clearly means you were going to call

The context makes the meaning clear, especially because the second clause mentions the number.

Because numara is the direct object of kaybettiniz, and it is a specific object.

• numara = number
• numarayı = the number / the specific number

The ending -yı is the accusative marker here.

So the sentence is talking about a particular number that both speaker and listener know about, not just any number in general.

In Turkish, the yes/no question particle usually comes after the element being questioned or focused.

So:

• Numarayı mı kaybettiniz?

means something like:

• Did you lose the number?
• more literally, Was it the number that you lost?

This placement gives focus to numarayı. It suggests the speaker is proposing that as the explanation:

• Was it the number you lost?

The particle mı/mi/mu/mü is written separately, though endings can attach to it if needed.

Kaybettiniz comes from kaybetmek = to lose.

Breakdown:

• kaybet- = lose
• -ti = past tense
• -niz = you plural or polite singular

So kaybettiniz means:

• you lost

Because of siz, it can mean either:

• you all lost
• you (formal/polite singular) lost

It can be either:

1. plural you: talking to several people
2. polite/formal singular you: talking respectfully to one person

Turkish uses siz and -nız/-niz for both.

Without more context, both are grammatically possible. In everyday conversation, many learners will interpret it as either:

• you all were going to call or
• you were going to call (polite)

It sounds mildly reproachful, surprised, or challenging.

A natural English feeling would be something like:

• But you were going to call; did you lose the number?
• You were supposed to call — did you lose the number or what?

The speaker seems to be pointing out that the other person failed to do what was expected, then offering a possible explanation.

So the tone is not neutral; it carries a sense of:

• expectation
• disappointment
• irony, sometimes

The semicolon separates two closely related thoughts:

• Hâlbuki siz arayacaktınız
• numarayı mı kaybettiniz?

It creates a stronger pause than a comma and helps show the contrast:

• first: you were supposed to call
• second: did you lose the number?

In ordinary writing, punctuation may vary. You might also see a comma or dash in similar sentences. The meaning stays basically the same.

You may see both hâlbuki and halbuki.

The circumflex in hâl is traditional and can indicate vowel length or historical spelling, but in modern everyday Turkish many people simply write halbuki.

So:

• hâlbuki = correct/traditional spelling
• halbuki = very common modern spelling

As a learner, it is good to recognize both forms as the same word.