Lesson 4: Numbers 21-100

¡Seguimos contando! (We keep counting!)

Welcome to Lesson 4! Now that you've mastered 1-20, it's time to expand your number knowledge. Being able to count to 100 lets you discuss prices, ages, years, addresses, and much more. Let's build on what you learned!

Part 1: The Tens (Las Decenas)

First, let's learn the "round" tens - these are the building blocks for all numbers up to 100.

The Ten Numbers

Pattern Recognition

Notice the pattern for 50-90:
- 50: cinc(o) + uenta = cincuenta
- 60: se(is) + enta = sesenta
- 70: set(e) + enta = setenta (note: "siete" loses "ie")
- 80: och(o) + enta = ochenta
- 90: nov(e) + enta = noventa (note: "nueve" → "nov")

💡 Teacher's Tip: The tens 30, 40, 50-90 all end in "-enta" or "-inta". This pattern makes them easy to remember!

Part 2: Numbers 21-29 (Veintiuno a Veintinueve)

These numbers combine "veinte" (20) with the ones digit, written as ONE word.

The "Veinti-" Pattern

Key Points

1. Written as ONE word: veintiuno (not "veinte y uno")
2. "Veinte" becomes "veinti-": veinte + uno = veintiuno
3. Accent marks on some: veintidós, veintitrés, veintiséis
4. Gender agreement with 21:
   - veintiún libros (21 books - masculine)
   - veintiuna casas (21 houses - feminine)

⚠️ Important: Only numbers 21-29 are written as one word. From 31 onwards, use three separate words!

Part 3: Numbers 31-99 (The "Y" Pattern)

From 31 onwards, numbers follow a simple, consistent pattern: [tens] + y + [ones]

The Pattern: treinta y uno, cuarenta y dos, etc.

Formula: [tens word] + y (and) + [ones word]

Examples:
- 31 = treinta y uno (30 and 1)
- 42 = cuarenta y dos (40 and 2)
- 55 = cincuenta y cinco (50 and 5)
- 67 = sesenta y siete (60 and 7)
- 73 = setenta y tres (70 and 3)
- 88 = ochenta y ocho (80 and 8)
- 99 = noventa y nueve (90 and 9)

Written as THREE Separate Words

Unlike 21-29, these are three words with spaces:
- ✅ treinta y cinco (35)
- ❌ treintaycinco (wrong - no spaces)

More Examples by Tens

30s:
- 31: treinta y uno
- 35: treinta y cinco
- 39: treinta y nueve

40s:
- 41: cuarenta y uno
- 45: cuarenta y cinco
- 49: cuarenta y nueve

50s:
- 51: cincuenta y uno
- 55: cincuenta y cinco
- 59: cincuenta y nueve

60s:
- 61: sesenta y uno
- 65: sesenta y cinco
- 69: sesenta y nueve

70s:
- 71: setenta y uno
- 75: setenta y cinco
- 79: setenta y nueve

80s:
- 81: ochenta y uno
- 85: ochenta y cinco
- 89: ochenta y nueve

90s:
- 91: noventa y uno
- 95: noventa y cinco
- 99: noventa y nueve

Part 4: The Number 100 (Cien vs. Ciento)

One hundred has TWO forms: cien and ciento

Cien (Exactly 100)

Use cien when saying exactly 100:
- cien = 100 (exactly)
- cien personas (100 people)
- cien años (100 years)
- cien dólares (100 dollars)

Ciento (101-199)

Use ciento for numbers 101-199:
- 101 = ciento uno
- 112 = ciento doce
- 150 = ciento cincuenta
- 199 = ciento noventa y nueve

💡 Rule: If it's exactly 100, use "cien". If it's more than 100, use "ciento".

Part 5: Practical Applications

Ages (Tengo X años)

Now you can say any age!
- Tengo veinticinco años. (I'm 25 years old)
- Tengo cuarenta y dos años. (I'm 42 years old)
- Tengo sesenta y siete años. (I'm 67 years old)
- Tengo noventa y tres años. (I'm 93 years old)

Prices (¿Cuánto cuesta?)

¿Cuánto cuesta? = How much does it cost?

Examples:
- Cuesta veinte euros. (It costs 20 euros)
- Cuesta cincuenta dólares. (It costs 50 dollars)
- Cuesta setenta y cinco pesos. (It costs 75 pesos)
- Cuesta noventa y nueve centavos. (It costs 99 cents)

Years (El año)

• mil novecientos noventa y nueve (1999)
• dos mil veinticinco (2025)
• But for now, focus on the last two digits:
• '99 (noventa y nueve)
• '25 (veinticinco)

Addresses (La dirección)

• Calle Principal, número treinta y cinco (35 Main Street)
• Avenida Central, número cuarenta y dos (42 Central Avenue)

Part 6: Phone Numbers

Spanish speakers often group phone numbers differently than English speakers.

Common Patterns

Spanish Number: 91-555-34-87

Said as pairs:
"noventa y uno, cinco cinco cinco, treinta y cuatro, ochenta y siete"

Or sometimes:
"nueve uno, cinco cinco cinco, tres cuatro, ocho siete"

Mobile Numbers

Spanish mobile numbers often start with 6 or 7:
- 612-345-678
"seis uno dos, tres cuatro cinco, seis siete ocho"

Part 7: Gender Agreement with Compound Numbers

Remember: Numbers ending in "uno" change for gender!

Masculine (uno/un)

• veintiún libros (21 books)
• treinta y un días (31 days)
• cuarenta y un años (41 years)

Feminine (una)

• veintiuna casas (21 houses)
• treinta y una personas (31 people)
• cuarenta y una páginas (41 pages)

Before Masculine Nouns

Drop the final "o" and use "ún" (with accent):
- veintiuno → veintiún
- treinta y uno → treinta y un
- cuarenta y uno → cuarenta y un

💡 Note: This ONLY applies to numbers ending in "uno" (21, 31, 41, 51, 61, 71, 81, 91). Other numbers don't change!

Part 8: Cultural Context - Money

Different Spanish-speaking countries use different currencies:

Common Currencies

• España: Euro (€) - el euro
• México: Peso mexicano - el peso
• Colombia: Peso colombiano - el peso
• Argentina: Peso argentino - el peso
• Perú: Sol - el sol
• Chile: Peso chileno - el peso
• USA (Hispanic areas): Dólar - el dólar

Talking About Prices

• Cuesta cincuenta euros. (It costs 50 euros)
• Son setenta y cinco pesos. (They are 75 pesos)
• Vale cuarenta dólares. (It's worth 40 dollars)

Part 9: Memory Techniques

Chunking Method

Break numbers into chunks:
- 68 = "sesenta" (60) + "y ocho" (and 8)
- Think: "60... and... 8"
- Say it in chunks: "se-SEN-ta y OH-cho"

Anchor Numbers

Memorize these "anchor" numbers first:
- 30, 40, 50, 60, 70, 80, 90, 100
- Then add the ones digit (1-9) using "y"

Pattern Practice

Practice counting by tens:
"diez, veinte, treinta, cuarenta, cincuenta, sesenta, setenta, ochenta, noventa, cien"

Then practice adding ones:
"treinta y uno, treinta y dos, treinta y tres..." (31, 32, 33...)

Real-World Practice

• Read license plates in Spanish
• Say prices out loud when shopping
• Read page numbers in books
• Tell time (more on this in future lessons!)

Part 10: Common Mistakes to Avoid

❌ Mistake 1: Writing 31+ as one word

• Wrong: "treintaycinco" (35)
• Right: "treinta y cinco" (three separate words)

❌ Mistake 2: Forgetting "y" (and)

• Wrong: "cuarenta cinco"
• Right: "cuarenta y cinco"

❌ Mistake 3: Using "ciento" for exactly 100

• Wrong: "ciento personas"
• Right: "cien personas" (exactly 100)

❌ Mistake 4: Not changing "uno" for gender

• Wrong: "treinta y uno casas"
• Right: "treinta y una casas" (feminine)

❌ Mistake 5: Mixing up "cuarenta" (40) and "cuatro" (4)

• Listen to the ending: -o vs. -enta
• cuatro (4), cuarenta (40)

Complete Number Reference Chart

The Tens

Sample Compound Numbers

• 25: veinticinco (one word)
• 35: treinta y cinco (three words)
• 47: cuarenta y siete
• 56: cincuenta y seis
• 68: sesenta y ocho
• 79: setenta y nueve
• 84: ochenta y cuatro
• 92: noventa y dos
• 100: cien

Practice Exercises

Exercise 1: Count by Tens

Say out loud:
10, 20, 30, 40, 50, 60, 70, 80, 90, 100

Exercise 2: Count by Fives

25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100

Exercise 3: Random Numbers

Practice saying these:
- 33, 48, 57, 61, 72, 84, 95, 100

Exercise 4: Your Life in Numbers

Say in Spanish:
- Your age
- Your address number
- Your phone number
- Your birth year (last two digits)
- A price you recently paid

📚 Ready to Practice!

You can now count from 1 to 100 in Spanish! This unlocks countless real-world situations.

Daily Practice:
1. Count by tens from 10-100
2. Practice saying random two-digit numbers
3. Read prices and say them in Spanish
4. Count by fives from 5-100

Key Skills to Master:
- Recognize and say all tens (30-90)
- Form compound numbers with "y"
- Distinguish between "cien" and "ciento"
- Apply gender changes with "uno"
- Use numbers in practical contexts (age, price, phone)

Coming Up:
You'll use these numbers constantly in future lessons for time, dates, measurements, and more!

Now complete your 50 practice exercises below! 👇