Learn Italian: La macchina è vecchia e costa duemila euro. - The car is old and costs two thousand euros.

The word for one thousand is mille. However, when you have two or more thousands, the plural form changes irregularly to -mila. Because of this, two thousand becomes duemila, three thousand is tremila, and so on.

Why doesn't euro change to "euri" in the plural?

In Italian, the word euro is invariable, meaning it never changes its ending for the plural. You say un euro (one euro) and due euro (two euros). Many foreign words and certain currency names behave this way.

Why is the adjective spelled vecchia and not vecchio?

Adjectives must match the gender and number of the noun they describe. Since macchina is a feminine singular noun, the standard dictionary form vecchio changes its ending to -a to become vecchia.

Why is there an "h" in vecchia?

In Italian, the letter c followed by i or e makes a soft sound (like the "ch" in "cheese"). To keep the hard "k" sound from the masculine word vecchio when making it feminine, an h must be inserted, creating vecchia.