Section 5.4 · Numbers function as adjectives of quantity and come before the noun — only uno and quantity words change to match gender and number
Numbers function as adjectives of quantity in Spanish. They usually come before the noun. While most numbers are constant and never change, the number one (uno) and its compounds change to match the gender of the noun — and quantity words like mucho, poco, todo agree in both gender and number.
This section covers four building blocks: the foundation numbers 0–10, the teens 11–20, counting by tens to 100, and the agreement rules for uno and ciento. Combined with the general quantity words, these tools let you count, estimate, and describe amounts in any everyday situation.
| Number | Rule | Masculine Example | Feminine Example |
|---|---|---|---|
| uno | Becomes un before masc. noun, una before fem. noun | un libro · un amigo | una carta · una amiga |
| ciento | Becomes cien when directly before a noun | cien libros | cien personas |
| mucho | Agrees in gender & number with noun | mucho trabajo · muchos libros | mucha gente · muchas flores |
| poco | Agrees in gender & number with noun | poco tiempo · pocos estudiantes | poca agua · pocas sillas |
| todo | Agrees in gender & number with noun | todo el trabajo · todos los días | toda la semana · todas las lecciones |
These are the foundation for all counting. Practice these until they are automatic. The numbers 0–10 are entirely unique words with no internal logic connecting them — they must be memorized individually. They function as adjectives before nouns: dos sillas, tres cafés, cuatro personas. Most of these numbers never change for gender or number — the only exception in this group is uno, which drops its final o before a masculine noun (un libro) and uses una before a feminine noun (una carta). All other numbers 2–10 stay constant regardless of the noun's gender.
Numbers 11 through 15 have completely unique names that must be memorized: once, doce, trece, catorce, quince. From 16 to 19, the names are combinations of "ten and [number]" written as single words: dieciséis (diez y seis → dieciséis), diecisiete, dieciocho, diecinueve. Note that dieciséis requires an accent mark on the é — it is the only teen with an accent. The number 20 (veinte) is also unique. Like numbers 2–10, these numbers do not change for gender — they stay the same before masculine or feminine nouns.
Once you know the tens, you can combine them with smaller numbers to count very quickly. The tens are: veinte (20), treinta (30), cuarenta (40), cincuenta (50), sesenta (60), setenta (70), ochenta (80), noventa (90), cien (100). To form numbers between tens, add y (and): treinta y uno, cuarenta y cinco, sesenta y tres. Note that cien is the form used for exactly 100. For 101 and above, the full form ciento is used: ciento uno, ciento veinte. Like other numbers, the tens do not change for gender — they are invariable adjectives.
The number one (uno) changes to un before a masculine noun and una before a feminine noun. The standalone form uno is used only when counting aloud or referring to the number itself — never directly before a noun. Similarly, ciento becomes cien when followed directly by a noun. Cien libros, cien personas, cien días — the shortened cien is always used before any noun. The full ciento is reserved for compound numbers above 100: ciento uno, ciento cincuenta.
When you do not have an exact number, you use words like "much," "some," or "all." Unlike cardinal numbers (dos, cinco, veinte), these quantity words must agree in gender and number with the noun they modify. Mucho becomes mucha, muchos, muchas; poco becomes poca, pocos, pocas; todo becomes toda, todos, todas; and algunos / algunas distinguish masculine and feminine. The one exception is suficiente (enough) — it is gender-neutral and does not change.
These six quantity words are the most essential indefinite quantifiers. Each one (except suficiente) changes to match the gender and number of the noun it modifies.
Listen to each sentence in Spanish, then repeat it aloud during the countdown pause.
Each sentence contains a number or quantity word in context. As you listen, identify the number and confirm it appears before the noun. In sentences 16–20, pay attention to un/una and cien — the context will make the gender choice clear. Sentences 21–25 feature general quantity words — notice how mucho, poco, todo, and algunos change form to match their nouns.
Step 1 — Listen: The Spanish sentence plays automatically. Focus on the number or quantity word — and notice what noun follows it.
Step 2 — Repeat: During the 4-second countdown, say the sentence aloud — practice the smooth flow of number + noun as a natural unit.
Step 3 — Adjust: Use the Speed and Volume sliders to find your ideal practice pace.
Count along: For sentences 1–15 (foundation, teens, and tens), mentally picture the quantity as you say each number. Attaching a visual image to each number accelerates memorization.
Check agreement for quantity words: In sentences 21–25, pause after the quantity word and ask: Is the noun masculine or feminine? Singular or plural? Does the form I heard match? This builds the agreement reflex automatically.
Practice the dieciséis accent: Sentence 10 includes dieciséis — the only teen with a written accent mark. Hear and repeat it several times to internalize both the pronunciation and the spelling.
Choose the correct answer. 20 questions drawn randomly from a pool of 25.