Pišem broj na papiru.

In Serbian, the verb ending often already shows the subject.

• pišem = I write / I am writing
• The ending -em tells you it is 1st person singular: I

So ja is usually omitted unless you want to emphasize it:

• Pišem broj na papiru. = I’m writing a number on paper.
• Ja pišem broj na papiru. = I’m the one writing a number on paper / extra emphasis on I

This is very common in Serbian.

Pišem is present tense.

From context, the Serbian present tense can correspond to either:

• I write
• I am writing

In this sentence, the natural English meaning is usually I am writing a number on paper, but grammatically Serbian simply uses the present tense pišem.

The dictionary form is pisati, meaning to write.

So:

• pisati = to write
• pišem = I write / I am writing

This verb is imperfective, so it focuses on the action as ongoing, repeated, or not viewed as completed.

Because broj is the direct object of the verb pišem, and here it is in the accusative case.

However, broj is a masculine inanimate noun, and for many masculine inanimate nouns, the accusative singular looks the same as the nominative singular.

So:

• nominative: broj
• accusative: broj

That is why the form does not change here.

Serbian has no articles like English a/an and the.

So broj can mean:

• a number
• the number

And na papiru can mean:

• on paper
• on the paper
• sometimes even on a sheet of paper, depending on context

The exact meaning is usually understood from the situation.

This is a very important Serbian pattern.

With na, the case depends on the meaning:

• na + accusative = movement onto something
• na + locative = location on something

Here the meaning is location/surface, not movement:

• Pišem broj na papiru. = I am writing a number on paper

So Serbian uses:

• na papiru = on paper / on the paper

If you said na papir, that would suggest motion toward the paper, as in putting something onto it, not simply being on it.

Papiru is locative singular.

The noun is:

• dictionary form: papir = paper

After na with the meaning on, Serbian uses the locative, so:

• papir → na papiru

So in this sentence:

• na papiru = on the paper / on paper

It can be both.

Literally:

• Pišem broj na papiru. = I’m writing a number on paper.

But na papiru can also be abstract, like English on paper:

• To dobro izgleda na papiru. = That looks good on paper.

So the phrase is useful both literally and figuratively.

Yes. Serbian word order is more flexible than English because case endings help show the grammatical roles.

The neutral order here is:

• Pišem broj na papiru.

But you may also hear:

• Broj pišem na papiru. — emphasizing broj
• Na papiru pišem broj. — emphasizing where I’m writing it

All are grammatical, but they differ in focus and style. The original sentence is the most straightforward and neutral.

Roughly:

• pišem ≈ PEE-shem

A little more precisely:

• pi sounds like pee
• š sounds like English sh
• em like em

So:

• pišem = PEE-shem

Also:

• broj is roughly broy
• papiru is roughly pah-PEE-roo

Usually pisati / pišem strongly suggests writing, especially by hand, but it can also be used more broadly depending on context.

For example, it can refer to:

• writing words or numbers
• writing a letter
• writing a message

If you want to be very specific about typing, Serbian often uses verbs related to typing, such as kucati in everyday speech.

So in Pišem broj na papiru, the image is naturally writing by hand on paper.