Transcript Prime Numbers

Prime
Factors
Saturday, 02 April 2016
Objective
Write a number as a product of
its prime factors.
Find the HCF and LCM of two
numbers
Prime Numbers
A prime number is a number that can
only be divided (exactly) by itself and 1.
12 ÷ 2 = 6
12 ÷ 3 = 4
12 ÷ 6 = 2
7÷7=1
7÷1=7
12 can be divided by 2, 4
and 6 so 12 is not a prime
number.
7 can only be divided by
itself and 1 to give an
integer answer. 7 is a
prime number
Write down the prime numbers between 1 and 40.
1
11
21
31
2
12
22
32
3
13
23
33
4
14
24
34
5
15
25
35
6
16
26
36
7
17
27
37
8
18
28
38
9
19
29
39
10
20
30
40
1
11
21
31
2
12
22
32
3
13
23
33
4
14
24
34
5
15
25
35
6
16
26
36
7
17
27
37
8
18
28
38
9
19
29
39
10
20
30
40
Factors
Factors are the numbers that multiply
together to give a certain number.
The factor pairs of 12 are:
1 x 12 = 12
2 x 6 = 12
3 x 4 = 12
4 x 3 = 12
6 x 2 = 12
12 x 1 = 12
The prime factors of 12 are:
2 x 2 x 3 = 12
Prime numbers
12
6
3
2
2
Find the Highest Common Factor (HCF) of
36 and 72
1. Find the prime factors of both numbers
36 = 2 x 2 x 3 x 3
72 = 2 x 2 x 2 x 3 x 3
2. Use one of each of the numbers that are in
both lists
HCF = 2 x 2 x 3 x 3
HCF = 36
Find the Lowest Common Multiple (LCM)
of 36 and 90
1. Find the prime factors of both numbers
36 = 2 x 2 x 3 x 3
90 = 2 x 3 x 3 x 5
2. Use one of each of the numbers that are in
both lists and all the remaining numbers.
LCM = 2 x 3 x 3 x 2 x 5
LCM = 180
1. Find the HCF of 12 and 30.
1. 6
2. Find the HCF of 54 and 180.
2. 18
3. Find the LCM of 18 and 30.
3. 90
4. Find the LCM of 24 and 84.
4. 168
5. Find the LCM of 54 and 120
6. Find the LCM of 72 and 150