Du må skrive navnet ditt riktig.

Må is a modal verb meaning must or have to.

So Du må skrive navnet ditt riktig means that writing the name correctly is necessary or required.

A useful thing to know: in everyday Norwegian, må can sometimes sound a bit less harsh than English must, and may feel closer to have to depending on context.

Because it comes after the modal verb må.

In Norwegian, after modal verbs such as må, kan, skal, vil, and bør, the next verb is normally in the infinitive:

• Du må skrive = You must write
• Jeg kan skrive = I can write
• Vi skal skrive = We will / are going to write

So skrive stays in its basic dictionary form.

After a modal verb, Norwegian normally does not use å.

Compare:

• Du må skrive = You must write
• Jeg liker å skrive = I like to write

So:

• after må → skrive
• not må å skrive

That is one of the most common patterns in Norwegian grammar.

Because Norwegian usually uses the definite form of the noun when a possessive comes after it.

Here:

• navn = name
• navnet = the name
• navnet ditt = your name

This may look strange to an English speaker, because English says your name, not the name your. But in Norwegian, definite noun + possessive is a very common structure.

So navnet ditt is the normal way to say your name here.

Because Norwegian often puts the possessive after the noun:

• navnet ditt = your name
• boka mi = my book
• vennen hans = his friend

This is usually the most natural and everyday pattern.

You can also put the possessive before the noun:

• ditt navn

But that often sounds more formal, more emphatic, or more contrastive. In ordinary speech, navnet ditt is the more natural choice.

Because navn is a neuter noun.

Its forms are:

• et navn = a name
• navnet = the name

For the possessive your, Norwegian changes the form depending on gender and number:

• din for common-gender singular nouns
• ditt for neuter singular nouns
• dine for plural

So:

• boka di = your book
• huset ditt = your house
• navnet ditt = your name
• bøkene dine = your books

Since navn is neuter, ditt is correct.

Because sin / si / sitt / sine is used only for a third-person possessor that refers back to the subject.

Examples:

• Han skriver navnet sitt = He is writing his own name
• Hun skriver boka si = She is writing her own book

But with du, you use din / ditt / dine, not sin:

• Du skriver navnet ditt = You are writing your name

So in this sentence, ditt is correct because the subject is du.

Here riktig means correctly.

It describes how you must write the name, so in English it is best translated as an adverb:

• skrive navnet ditt riktig = write your name correctly

Even though English uses correctly, Norwegian uses riktig here.

A helpful point: riktig can also be an adjective meaning correct or right, but in this sentence it functions adverbially.

Because it modifies the action skrive navnet ditt and Norwegian often places this kind of word after the object.

Structure here:

• Du = subject
• må = finite verb
• skrive = infinitive
• navnet ditt = object
• riktig = tells how the action is done

So the sentence ends with the idea correctly.

That word order sounds natural in Norwegian:

• Du må skrive navnet ditt riktig

The sentence follows normal Norwegian main-clause word order:

Du + må + skrive + navnet ditt + riktig

More specifically:

• Du = subject
• må = finite verb
• skrive = main verb in infinitive
• navnet ditt = direct object
• riktig = adverb

A key rule in Norwegian is that in main clauses, the finite verb usually comes in the second position. That is why må comes right after Du.

Here du is singular: you talking to one person.

The plural form is dere:

• Du må skrive navnet ditt riktig = You must write your name correctly. (one person)
• Dere må skrive navnene deres riktig = You must write your names correctly. (more than one person)

Also, modern Norwegian usually uses du even in situations where some other languages would use a formal you.