Highest common factor and lowest common multiple – The first example finds the highest common factor of 6 and 15 by listing all the factors of each number, highlighting all the common factors and indicating the highest common factor. A similar technique is used to find the lowest common multiple of 6 and 15.
Highest common factor and lowest common multiple using prime factorisation – The video explains that the method used in the first video can be time consuming when dealing with larger numbers. The example begins by finding the prime factors of 60 and of 72 using factor trees. Each number is then written as a product of its prime factors and the highest common factor and the lowest common multiple is found. The videos are produced by MathsMaster.org