Let's solve the problem step by step, based on the image you provided.
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Problem:
Find the
common factors of 40 and 45, and then determine the
greatest common factor (GCF).
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Step 1: List all the factors of each number
We are given:
- Factors of
40:
$ 1, 2, 4, 5, 8, 10, 20, 40 $
- Factors of
45:
$ 1, 3, 5, 9, 15, 45 $
>
✔ These lists are correct.
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Step 2: Identify the common factors
Now, find the numbers that appear in
both lists.
- Common factors of 40 and 45:
$ 1, 5 $
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Step 3: Find the greatest common factor
From the common factors $ 1 $ and $ 5 $, the
greatest one is:
>
✔ 5
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✔ Final Answer:
-
Common factors of 40 and 45: $ 1, 5 $
-
Greatest Common Factor (GCF): $ \boxed{5} $
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📌 Explanation:
The
greatest common factor (GCF) is the largest number that divides both numbers without a remainder. In this case, 5 is the largest number that divides both 40 and 45 evenly.
✔ Example check:
- $ 40 ÷ 5 = 8 $
- $ 45 ÷ 5 = 9 $
Both are whole numbers → 5 is indeed a common factor, and it's the greatest.
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Let me know if you'd like to see how to use prime factorization for this too!
Parent Tip: Review the logic above to help your child master the concept of greatest common factor ppt.
