Greatest Common Factor | How to Find the Greatest Common Factor (GCF)

Summary

In this educational video, Mr. J teaches viewers how to determine the greatest common factor (GCF) of two numbers. The process involves listing all factors of each number and identifying the largest factor they share. Mr. J walks through several examples, starting with 10 and 15, then 12 and 6, and finally 20 and 10, and 9 and 21, demonstrating the method for both even and odd numbers. The video is designed to help students understand the concept of factors and how to apply them to find the GCF effectively.

Takeaways

• 📚 The video is a math lesson focused on finding the greatest common factor (GCF) of two numbers.
• 🔢 A factor is a number that can multiply together to give another number.
• 👉 To find the GCF, list all factors of each number and identify the largest common one.
• 🌰 The example given starts with the numbers 10 and 15, and the factors of 10 are 1, 2, 5, and 10.
• 📝 For the number 15, the factors are 1, 3, 5, and 15, with 5 being the GCF with 10.
• 🧩 The video demonstrates the process with additional examples, such as 12 and 6, where the GCF is 6.
• 🤔 It encourages viewers to try some problems on their own before revealing the solution.
• 📉 For the numbers 20 and 10, the factors are listed, and the GCF is found to be 10.
• 🤹‍♂️ The lesson includes a mix of even and odd numbers, like 9 and 21, with 3 as their GCF.
• 📝 The importance of using the list of factors already known, like recognizing 10's factors from the previous example, is emphasized.
• 🎓 The video concludes by summarizing the concept of GCF and thanking viewers for watching.

Q & A

What is the main topic of the video?

The main topic of the video is how to find the greatest common factor (GCF) between two numbers.

What is a factor according to the video?

A factor is a number that can multiply together to give you another number.

How does the video suggest listing the factors of a number?

The video suggests starting with 1 and the number itself, then listing other factors in between, with pairs that multiply to give the original number.

What is the greatest common factor of 10 and 15 according to the video?

The greatest common factor of 10 and 15 is 5.

What factors does the video list for the number 12?

The factors listed for 12 are 1, 2, 3, 4, 6, and 12.

What is the greatest common factor of 12 and 6?

The greatest common factor of 12 and 6 is 6.

How does the video approach finding the GCF for 20 and 10?

The video lists the factors of 20 (1, 2, 4, 5, 10, 20) and 10 (1, 2, 5, 10) and identifies the greatest common factor, which is 10.

What is the greatest common factor of 9 and 21 as per the video?

The greatest common factor of 9 and 21 is 3.

What is the significance of listing factors in pairs according to the video?

Listing factors in pairs helps to visualize and understand how different numbers can multiply to give the original number.

Why does the video mention that spacing is not as important when listing factors?

The video mentions that as long as all the factors are listed, the exact spacing between them is not crucial for finding the GCF.

What is the video's advice for finding the GCF when one of the numbers is prime?

The video suggests that if one of the numbers is prime, you will only have 1 and that prime number itself as factors, which simplifies the process of finding the GCF.