How to use "years old" versus "year old"

Rule: Use “year old” when describing a singular noun (like boy, girl, student, car). Use “years old” when not followed by a noun — when it just states the person’s age.

✅ Examples: 1️⃣ When you use a noun → “year old” ➡️ Structure: [number]-year-old + noun She is a 10-year-old girl. My brother is a 7-year-old student. They bought a 5-year-old car.

2️⃣ When you don’t use a noun → “years old” ➡️ Structure: [number] years old She is 10 years old. My brother is 7 years old. Their car is 5 years old.

Quick Trick to Remember: If you can remove the noun and the sentence still makes sense → use years old. If you need it to describe a noun → use year old. 💬 Example: ✅ She is a 6-year-old girl. ✅ She is 6 years old. ❌ She is 6-year-old. (✖ no noun after it)

PART 1: Choose the correct form choose between “year old” and “years old.”) 1. My sister is eight ______. 2. I have a three-______ cat. 3. That tall boy is fourteen ______ already! 4. We adopted a one-______ puppy last week. 5. Mr. Chen is fifty-two ______. 6. I met a six-______ dancer yesterday. 7. My grandma is 80 ______ but still strong! 8. That school has a 100-______ history.

PART 2: Fix the Mistakes (Each sentence has an error. You must correct it.) 1. My brother is a 10-years-old boy. 2. She’s only 4-year-old. 3. That 20-years-old car still works! 4. I am twenty-one year old. 5. Their daughter is 3-years old.

My son is two years old, but I call him my two-year-old baby.” 👉 Why are both correct?

Rule Summary: The hyphen (-) is required when “year old” works as an adjective (to describe a noun). When it’s not describing a noun, you don’t use hyphens.

✅ With Hyphen (Correct): Used before a noun (as an adjective phrase) 🔹 She is a 5-year-old girl. 🔹 I have a 2-year-old phone. 🔹 He met a 60-year-old teacher. ❌ Without Hyphen (Incorrect): ✖ She is a 5 year old girl. ✖ I met a 60 year old teacher.

✅ No Hyphen (When No Noun After It): When it doesn’t describe a noun, you do not use hyphens. 🔹 She is 5 years old. 🔹 My phone is 2 years old. 🔹 The teacher is 60 years old.