What is the Greatest Common Factor (GCF)?
The Greatest Common Factor (GCF) is the largest number that divides evenly into two or more numbers.
When working with three or four numbers, we're looking for the biggest number that is a factor of all the numbers in the set. It's like finding the biggest puzzle piece that fits perfectly into all the different number puzzles!
How to Find the GCF of Multiple Numbers
1️⃣ List the factors of each number
2️⃣ Identify the common factors that appear in all lists
3️⃣ Choose the largest number from the common factors
Let's Practice with Examples!
Example 1: Find the GCF of 12, 18, and 24
Step 1: List the factors of each number:
- 12: 1, 2, 3, 4, 6, 12
- 18: 1, 2, 3, 6, 9, 18
- 24: 1, 2, 3, 4, 6, 8, 12, 24
Step 2: Common factors are: 1, 2, 3, 6
Step 3: The largest common factor is 6!
✅ So, GCF(12, 18, 24) = 6
Example 2: Find the GCF of 15, 30, 45, and 60
Step 1: List the factors of each number:
- 15: 1, 3, 5, 15
- 30: 1, 2, 3, 5, 6, 10, 15, 30
- 45: 1, 3, 5, 9, 15, 45
- 60: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60
Step 2: Common factors are: 1, 3, 5, 15
Step 3: The largest common factor is 15!
✅ So, GCF(15, 30, 45, 60) = 15
Parent Tips 🌟
- Factor Hunt Game: Make it fun by turning GCF into a treasure hunt - have your child find household items that come in different quantities (like 12 eggs, 18 cookies, 24 crayons) and find their GCF.
- Real-world Connections: Show how GCF is used in real life, like dividing snacks equally among friends or arranging items in equal groups.
- Prime Factorization Shortcut: Once your child masters listing factors, introduce the prime factorization method for finding GCF with larger numbers.