GCSE Secondary Maths Age 13-17 - Number: LCM and HCF - Explained

The video tutorial explains how to find the lowest common multiple (LCM) of 40 and 56 by using factor trees to break down each number into its prime factors. It then combines these factors to calculate the LCM, which is 280. The tutorial also covers finding the highest common factor (HCF) of two numbers, A and B, by identifying and multiplying their common prime factors, resulting in an HCF of 60. The video provides step-by-step guidance and allocates marks for each part of the problem-solving process.

What is the prime factorization of 40?

• 2 x 2 x 5

• 3 x 3 x 5

• 2 x 3 x 5

• 2 x 2 x 2 x 5

Which of the following is a prime factor of 56?

• 5

• 7

• 3

• 9

What is the LCM of 40 and 56?

• 320

• 280

• 240

• 360

Which common factor is shared by both A and B?

• 2 cubed

• 3

• 5 squared

• 7

What is the HCF of A and B?

• 50

• 60

• 40

• 30