1. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. To find a solution for a question about highest common factors. Objectives

2. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Find the highest common factor of 24 and 36. Firstly draw factor trees for both numbers. 24 212 2 6 23 Divide by 2 if you can. Notice that branches stop once you reach a prime number.

3. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Find the highest common factor of 24 and 36. Firstly draw factor trees for both numbers 24 212 2 6 23 36 218 2 9 33

4. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Find the highest common factor of 24 and 36. Firstly draw factor trees for both numbers. 24 2 2 23 36 218 2 9 33

5. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Find the highest common factor of 24 and 36. Firstly draw factor trees for both numbers. 24 = 2 x 2 x 2 x 3 2 2 23 36 218 2 9 33

6. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Find the highest common factor of 24 and 36. Firstly draw factor trees for both numbers. 24 = 2 x 2 x 2 x 3 36 218 2 9 33

7. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Find the highest common factor of 24 and 36. Firstly draw factor trees for both numbers. 24 = 2 x 2 x 2 x 3 36 2 2 33

8. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Find the highest common factor of 24 and 36. Firstly draw factor trees for both numbers. 24 = 2 x 2 x 2 x 3 36 = 2 x 2 x 3 x 3 2 2 33

9. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Find the highest common factor of 24 and 36. Firstly draw factor trees for both numbers. 24 = 2 x 2 x 2 x 3 36 = 2 x 2 x 3 x 3 Now pick out everything that is common to both.

10. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Find the highest common factor of 24 and 36. Now pick out everything that is common to both. 24 = 2 x 2 x 2 x 3 36 = 2 x 2 x 3 x 3 2

11. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Find the highest common factor of 24 and 36. Now pick out everything that is common to both. 24 = 2 x 2 x 2 x 3 36 = 2 x 2 x 3 x 3 2 x 2

12. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Find the highest common factor of 24 and 36. Now pick out everything that is common to both. 24 = 2 x 2 x 2 x 3 36 = 2 x 2 x 3 x 3 2 x 2 x 3

13. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Find the highest common factor of 24 and 36. Now pick out everything that is common to both. 24 = 2 x 2 x 2 x 3 36 = 2 x 2 x 3 x 3 2 x 2 x 3 = 12

14. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Find the highest common factor of 24 and 36. Now pick out everything that is common to both. 24 = 2 x 2 x 2 x 3 36 = 2 x 2 x 3 x 3 2 x 2 x 3 = 12 The highest common factor = 12

15. Edexcel GCSE Maths Spec B – Modular: Booster C © Pearson Education 2010. This document may have been altered from the original. Firstly find the factor trees for each number, stopping each branch when you hit a prime. Summary Next write each number as a product of primes. List all numbers that are common to both, including repeats. Multiply all numbers in your list to get the final answer.