Highest common factor and lowest common multiple
Highest common factor
A common factor is a that is shared by two or more numbers. For example, a common factor of 8 and 10 is 2, as 2 is a factor of 8, and 2 is also a factor of 10.The is found by finding all common factors of two numbers and selecting the largest one.
For example, 8 and 12 have common factors of 1, 2 and 4. The highest common factor is 4.
Question
Find the highest common factor of 9 and 21.
Lowest common multiple
A common multiple is a number that is a shared of two or more numbers. For example, 24 is a common multiple of 8 and 12, as 24 is in the 8 times tables (\(8 \times 3 = 24\)) and 24 is in the 12 times tables (\(12 \times 2 = 24\)).
The is found by listing the multiples of each number and circling any common multiples. The lowest one is the lowest common multiple.
Question
Find the lowest common multiple of 5 and 6.
