Mater ad nummularium ambulat, quia denarios in sestertios mutare vult.

Because Latin often uses ad + accusative to show motion toward a person or place.

So ad nummularium ambulat means she walks to the money-changer.

• ad = to, toward
• nummularium = accusative singular of nummularius

English can often say just she visits the banker or she goes to the banker, but Latin commonly marks that destination with ad.

Nummularius means a money-changer, banker, or someone who deals in coins.

In this sentence, nummularium is the accusative singular form, because it follows ad.

This is not just any random merchant: the word suggests someone who handles money, coin exchange, and related business.

Mater is the subject of the sentence, so it is in the nominative case.

The sentence is saying that the mother is doing the actions:

• ambulat = walks
• vult = wants

Since she is the one acting, Latin uses the nominative: mater.

If she were a direct object, then you would expect matrem instead.

Literally, ambulat means walks.

So the sentence specifically says that the mother walks to the money-changer, not just that she goes there in some unspecified way.

A learner might expect it for goes, but Latin often chooses a more specific verb when appropriate. Here ambulat gives a concrete picture: she is going there on foot.

Quia means because. It introduces the reason for the action in the main clause.

So the structure is:

• Mater ad nummularium ambulat = The mother walks to the money-changer
• quia ... vult = because she wants ...

This is very similar to English word order with because.

It is built into the verbs.

Latin verbs usually include the subject in their endings, so you often do not need a separate pronoun.

• ambulat = he/she/it walks
• vult = he/she/it wants

Because mater is already named, Latin does not need to add ea for she.

Because vult means wants, and Latin commonly uses an infinitive after verbs of wanting, being able, beginning, and so on.

So:

• vult mutare = wants to change/exchange

Here mutare is the infinitive, equivalent to English to exchange.

This is a very common Latin construction:

• vult ire = wants to go
• potest videre = can see
• debet laborare = ought to work

This is one of the most important things to notice in the sentence.

In denarios in sestertios mutare, Latin uses:

• the direct object in the accusative: denarios
• in + accusative to show what something is being changed into: in sestertios

So the meaning is:

• denarios = the coins she is exchanging
• in sestertios = into sestertii

A helpful way to think about it is:

• change X into Y
• mutare X in Y

That is why both forms end up connected with the accusative, though for different reasons.

They do different jobs in the exchange.

• denarios = the coins she currently has; these are the ones being exchanged
• sestertios = the coins she wants to receive

So denarios in sestertios mutare means to exchange denarii into sestertii.

Even if the English translation says change denarii for sestertii or exchange denarii into sestertii, the Latin structure is specifically X in Y.

They are:

• denarius, -i = a denarius
• sestertius, -i = a sestertius

In the sentence, both are accusative plural:

• denarios
• sestertios

These are second-declension masculine nouns, so the accusative plural ending is -os.

Latin word order is more flexible than English because the grammatical roles are shown by endings, not mainly by position.

English depends heavily on word order:

• The mother walks to the banker because she wants to exchange...

Latin can move words around more freely:

• Mater ad nummularium ambulat, quia denarios in sestertios mutare vult.

This sentence is actually fairly straightforward, but even here the infinitive mutare comes before vult, whereas English usually says wants to exchange.

Latin often places the main verb near the end of its clause, though this is not a rigid rule.

Yes. That is a very literal and accurate translation.

More natural English might say:

• because she wants to exchange denarii for sestertii
• because she wants to change her denarii into sestertii

But the Latin structure is very close to change denarii into sestertii.

It is the same word, but with a different sense.

Latin in can mean:

• in/on with the ablative for location
• into/onto with the accusative for motion or change toward a result

Here it is followed by the accusative sestertios, so it means into rather than in.

This fits the idea of transformation or exchange:

• mutare in = change into

Yes. Latin has several verbs for going or moving, depending on nuance.

For example:

• it = goes
• venit = comes
• ambulat = walks

The choice of ambulat emphasizes the manner of travel: she is walking to the money-changer.

Classical Latin has no definite or indefinite articles.

So mater can mean:

• mother
• the mother
• sometimes even a mother, depending on context

Likewise nummularium can mean:

• the money-changer
• a money-changer

The translator supplies the or a based on what makes sense in context.

Mutare is a broad verb meaning to change, alter, or exchange.

In this context, because the objects are coins and the destination is a money-changer, it clearly means to exchange money.

So the basic sense of the verb is broad, but the context makes the specific meaning obvious.