Numbers – Factors, Multiples and Prime Numbers

Factors, Multiples and Prime Numbers:

Multiples – products of a multiplication table

. e.g 20 is a multiple of 5, because it is a product of 5 x 4, as well as 4

Example:

Q) Find the lowest common multiple of 5 and 7

1. Write out the multiples of 5 and 7
2. Find the smallest multiple from both

A) 35

Factors – a factor is a number that can divide exactly into a given number without a remainder

. e.g 7 is a factor of 21 because 21 can be divided by 7, 3 times

– Therefore 3 is also a factor of 21 

Example:

Q) Find the highest common factor of 18 and 24

1. Write out the factors of 18 and 24 the numbers that multiply to get 18 and 24
2. Find the largest number that occurs on both sides

A) 6

Tips:

. Every whole number has a minimum of two factors one and itself

Prime Number – a number with only two factors 1 and itself

. e.g 2, 3, 5, 7, 11….

Example:

Q) Find 3 prime numbers that multiply to give 30

1. 30 is even so it can be divided by 2
2. 5 and 3 are both prime numbers that multiply to give 15

A) 5, 3 and 2

Tips:

. 1 is not a prime number as prime numbers have two factors but 1 only has one