Tant si arriba com si no, mira el número de seguiment.

It means whether ... or ... / whether ... or not.

So Tant si arriba com si no means whether it arrives or not.

This is a very common Catalan pattern: tant si X com si Y

In this sentence:

• X = arriba
• Y = no, with the verb understood

By itself, tant often means so much, so many, or as much. But in this fixed structure, tant si ... com si ..., it does not have that literal meaning anymore.

You should learn tant si ... com si ... as one chunk meaning whether ... or ....

Because Catalan normally repeats si in this pattern:

• tant si arriba com si no
• literally: whether if it arrives as if not

That literal breakdown sounds strange in English, but it is normal in Catalan. The repeated si is just part of the standard construction.

No. That is an important point.

Catalan com si can mean as if in other sentences, but not here. In this sentence, com si is part of the larger pattern tant si ... com si ....

So here it does not mean as if. It is just the second half of the whether ... or ... structure.

Because Catalan allows the verb to be omitted when it is already clear from the first part.

So:

• tant si arriba com si no means the same as
• tant si arriba com si no arriba

This is very similar to English:

• whether it arrives or not instead of
• whether it arrives or it does not arrive

The shorter version is perfectly natural.

Because they are different words.

• si no = if not
• sinó = but rather / except

In this sentence, it must be si no because it is the negative second half of the tant si ... com si ... pattern.

So:

• tant si arriba com si no = correct
• tant si arriba com sinó = incorrect

Because after this kind of si clause, Catalan normally uses the indicative, not the subjunctive.

So arriba is the normal choice here.

This is different from other structures where you may see the subjunctive. An English speaker may expect something more hypothetical, but with tant si ... com si ..., the indicative is standard.

Catalan often leaves out subject pronouns when the verb ending already shows the person, or when the subject is clear from context.

So arriba does not need an explicit subject. The subject is understood from the situation, probably something like:

• the package
• the order
• it

That is why Catalan can simply say arriba.

Mira is the informal singular imperative of mirar.

Here it means look at or more naturally check.

So the sentence is addressed to one person informally, using tu.

Related forms:

• mira = informal singular
• miri = formal singular
• mireu = informal plural
• mirin = formal plural

Yes. Although mirar basically means to look, in many contexts it can also mean to check or to look up.

So mira el número de seguiment is naturally understood as:

• check the tracking number
• look at the tracking number

In English, check is usually the most natural translation in this kind of context.

It means tracking number.

• número = number
• seguiment = tracking, follow-up

In delivery or shipping contexts, número de seguiment is the normal idea of a number used to track a package.

You may also see codi de seguiment, which means tracking code.

Because Tant si arriba com si no is an introductory clause, and the main instruction comes after it:

• Tant si arriba com si no, mira el número de seguiment.

The comma helps separate the introductory idea from the main command.

In English, you would often do the same:

• Whether it arrives or not, check the tracking number.

Yes. Some alternatives are possible, for example:

• Tant si arriba com si no arriba, mira el número de seguiment.
• Arribi o no, mira el número de seguiment.

The version you were given is natural and concise. It sounds idiomatic and avoids repeating arriba unnecessarily.