# EDEXCEL MATHS B: UNIT 2: Important Types of Numbers

EDEXCEL MATHS B: UNIT 2: Important Types of Numbers

PRIMES,MULTIPLES,FACTOR AND PRIME PRODUCT DECOMPOSTION, LCM AND HCF, SQUARE NUMBERS

- Created by: bec
- Created on: 13-11-12 16:18

First 230 words of the document:

Important Types of Numbers

FACTOR A factor of a number will divide exactly into the number.

Example The factors of 12 are 1, 2, 3, 4, 6 and 12

PRIME NUMBER A number with exactly two factors.

Example 11 is a prime number as its only factors are 1 and 11.

The first ten prime numbers are: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29

One is not a prime number as it only has one factor.

Two is the only even prime number

MULTIPLES These are numbers with a common factor (alternatively they are numbers in

the appropriate `times table').

Example The multiples of 3 are: 3, 6, 9, 12, 15, 18, 21, 24 ..........

PRIME FACTORS These are factors of a number which are also prime numbers.

Example The factors of 20 are 1, 2, 4, 5, 10 and 20

The prime factors of 20 are 2 and 5 (the prime numbers from the list of factors)

PRIME FACTOR DECOMPOSITION (or PRODUCT OF PRIMES)

Any nonprime number (except 1) can be written as the product of its prime factors.

We use a `factor tree' to help find the prime factors. Each number is written as a multiplication.

If one of the numbers is prime then that branch ends. It can help to circle the prime ends of the

branches.

Example Express 120 as a product of its prime factors

120 120

2 60 3 40

2 30 4 10

2 15 2 2 2 5

3 5

120 = 2 x 2 x 2 x 3 x 5 = 23 x 3 x 5 120 = 2 x 2 x 2 x 3 x 5 = 23 x 3 x 5

## Comments

No comments have yet been made