Ordinal numbers tell you order and sequence. In English, you say, first, second, third, and so on. In Spanish, the corresponding ordinal numbers are primero (pree-meh-roh) (first), segundo (seh-goon-doh) (second), and tercero (tehr-seh-roh) (third). These numbers are different from one, two, and three (those numbers are called cardinal numbers).
When given directions, you hear a lot of phrases describing things like the third block to the left or the fourth floor. So ordinal numbers are extremely useful. Here are the most common ordinals in Spanish:
primero (pree-meh-roh) (first)
segundo (seh-goon-doh) (second)
tercero (tehr-seh-roh) (third)
cuarto (kooahr-toh) (fourth)
quinto (keen-toh) (fifth)
sexto (sehks-toh) (sixth)
séptimo (sehp-tee-moh) (seventh)
octavo (ohk-tah-bvoh) (eighth)
noveno (noh-bveh-noh) (ninth)
décimo (deh-see-moh) (tenth)
Here are some phrases to help you practice using ordinal numbers:
Vivo en el octavo piso. (bvee-bvoh ehn ehl ohk-tah-bvoh pee-soh) (I live on the eighth floor.)
En la tercera calle hay un museo. (ehn lah tehr-seh-rah kah-yeh ahy oon moo-seh-oh) (At the third street there is a museum.)
Este es el cuarto cine que veo aquí. (ehs-teh ehs ehl kooahr-toh see-neh keh bveh-oh ah-kee) (This is the fourth cinema I’ve seen here.)
En el primer piso hay una florería. (ehn ehl pree-mehr pee-soh ahy oo-nah floh-reh-reeah) (On the first floor there is a flower shop.)
Voy a bajar al segundo piso. (bvohy ah bvah-Hahr ahl seh-goon-doh pee-soh) (I’m going down to the second floor.)
La terraza está en el décimonoveno piso. (lah teh-rrah-sah ehs-tah ehn ehl deh-see-moh-noh-bveh-noh pee-soh) (The terrace is on the nineteenth floor.)