Mám sto korun.

Because Czech usually does not need subject pronouns when the verb ending already shows who is doing the action.

• mám = I have
• the ending -m tells you it is 1st person singular

So Já mám sto korun. is also possible, but já is usually added only for emphasis, contrast, or clarity.

• Mám sto korun. = neutral: I have a hundred crowns.
• Já mám sto korun. = I have a hundred crowns. (maybe someone else does not)

Mám is the 1st person singular present tense form of the verb mít, which means to have.

A few present-tense forms of mít are:

• mám = I have
• máš = you have
• má = he/she/it has
• máme = we have
• máte = you all / you formal have
• mají = they have

So:

• Mám sto korun. = I have a hundred crowns.

Sto means one hundred.

It is the basic Czech word for 100.

Examples:

• sto korun = one hundred crowns
• sto lidí = one hundred people
• sto let = one hundred years

In this sentence, sto is the number modifying korun.

This is one of the most important number patterns in Czech.

After numbers:

• 1 → noun is usually singular: koruna
• 2, 3, 4 → noun is usually plural in a different form: koruny
• 5 and higher → noun is usually genitive plural: korun

So:

• jedna koruna = one crown
• dvě koruny = two crowns
• tři koruny = three crowns
• čtyři koruny = four crowns
• pět korun = five crowns
• sto korun = one hundred crowns

That is why sto korun is correct.

Yes. Korun is the genitive plural form of koruna.

The basic forms here are:

• koruna = singular
• koruny = plural form used after 2–4 in many situations
• korun = genitive plural, used after 5 and higher

So even though it may not look like an English plural, it definitely refers to more than one crown.

Because in Czech, number phrases have their own grammar.

The whole phrase sto korun functions as the object of mám, but inside that phrase, the numeral sto requires the noun to appear in the genitive plural.

So the structure is roughly:

• mám = I have
• sto korun = a hundred of crowns / one hundred crowns

This is normal Czech grammar after numbers 5 and above.

So even though English just says a hundred crowns, Czech uses a structure that includes genitive plural on the noun.

Yes. Koruna means crown, and in everyday Czech it usually refers to the Czech currency, the Czech crown.

So:

• sto korun usually means 100 Czech crowns
• you may also see 100 Kč, where Kč is the standard abbreviation

In everyday conversation, korun is very common when talking about prices and money.

Yes, absolutely.

In writing, especially with prices or amounts of money, Czech often uses the abbreviation Kč.

So these are both normal:

• Mám sto korun.
• Mám sto Kč.

The full word korun is more natural in normal speech, while Kč is very common in writing.

A simple approximate pronunciation is:

• Mám ≈ maam
• sto ≈ sto
• korun ≈ ko-roon

A few useful notes:

• á is a long a
• o is a clear short o
• u in korun sounds like oo
• stress in Czech is usually on the first syllable of each word:
  • MÁM
  • STO
  • KO-run

A rough English-style approximation: maam sto KO-roon

Yes. Czech word order is more flexible than English word order.

The neutral sentence is:

• Mám sto korun.

But other orders are possible for emphasis:

• Sto korun mám. = I do have a hundred crowns.
• Korun mám sto. = emphasis on the amount

These versions do not usually change the basic meaning, but they change the focus or style.

For a learner, Mám sto korun. is the safest and most neutral form.

A helpful breakdown is:

• Mám = I have
• sto = one hundred
• korun = crowns / of crowns

So literally it is something like:

• I have one hundred crowns

Or, if you want to see the grammar more literally:

• I-have hundred crowns-GEN.PL

That last version is not good English, but it helps explain why korun has that form.

No. You do not add jednu before sto here.

Sto already means one hundred, so it stands on its own.

Correct:

• Mám sto korun.

Not correct:

• Mám jednu sto korun.

If you want to say one crown, then you use:

• Mám jednu korunu.

So:

• jednu korunu = one crown
• sto korun = one hundred crowns

Mostly yes, and this is a very useful pattern to learn.

With koruna:

• 1 koruna
• 2 koruny
• 3 koruny
• 4 koruny
• 5 korun
• 10 korun
• 20 korun
• 100 korun

So the key split is:

• 1
• 2–4
• 5+

This pattern is very common in Czech, not only with money, but with many countable nouns.

Yes. In everyday speech, people often use more colloquial ways to talk about money.

For example:

• Mám stovku. = I have a hundred-crown note / I have a hundred.
• Mám sto kaček. = I have a hundred bucks. (informal/slangy)

But the standard, neutral sentence is:

• Mám sto korun.

That is the best version for a learner to know first.