This document discusses factors, division, and prime numbers. It provides examples of dividing numbers and determining factors. A number is prime if it has only two factors - 1 and itself. The document also introduces the concepts of greatest common divisor (GCD) and least common multiple (LCM), providing examples of finding the GCD and LCM of pairs of numbers. Exercises are included for readers to find the GCD and LCM of additional number pairs.

1. 1. Factors
• What is the factors?

2. What does the symbol “÷” and “ = ” mean?
12÷3 = 4
18÷9 = 2
15÷4 = 3R3
Review

3. The symbol “ ” is “ division”
The symbol “ = ” is “ division”
Therefore
12÷3 = 4
We can read that “ twelve divide
three equals four

4. • 18÷9 = 2
• We can read that “ eight
divide nine equals two

5. • What about?
15÷4 = ?

6. 12÷3 = 4
If 12 can be divided by 3, so 3 is a factor of 12
18÷9 = 2
If 18 can be divided by 9, so 9 is a factor of 18
15÷4 = 3.75
If 15 cannot be divided by 4, so 4 is not a factor of 15

7. (A) Determine whether the given number is a
factor of the number in brackets.
• (a). 2 (14)
• (b). 5 (120)
• (c). 8 (124)
• (d). 12 (106)
• (e). 15 (145)
• (f). 21 (105)

8. (B) List the factors of a whole
number

10. 24
2 12
2 6
2 3
List down all the factors of 24
1
24 can be divided by 2, 3, 6, 12 and 24.
So, the factors of 24 are 2, 3, 6, 12 and 24.

11. 2. Prime factors
• (A) Prime numbers
A prime number is a
whole number that
has only two factors,
that is 1 and itself.

12. Example
•Determine whether the
following are prime
numbers: 4, 6, 7, 9, and
13

13. • 4 has three factors: 1, 2,and 4
4 prime number.

14. • 7 has two factors: 1 and 7
7 is a prime number

15. • 9 has three factors: 1, 3 and 9
9 is not a prime number

16. • 13 has two factors: 1 and 13
13 is a prime number

17. • prime numbers from 1-100have 25 numbers:
2, 3, 5, 7, 11, 13, 17, 19, 23, 29,
31, 37, 41, 43, 47, 53, 59, 61, 67,
71, 73, 79, 83, 89 and 97

18. Greatest Common Divisor (GCD)
Example Find the common divisor and the greatest common factor
(GCD) of 8 and 20
factor of 8 = 1, 2, 4 and 8.
factor of 20 are 1, 2, 4, 5, 10 and 20
1, 2, 4 are the common divisors of 8 and 20
4 is the greatest common divisor of 8 and 20

19. Exercise 1
• Find the GCD of following pairs of number.
• 1) 2, 15……………..
• 2) 5, 10……………..
• 3) 12, 2……………..
• 4) 8, 40……………..
• 5) 6, 8………………..

20. Least common multiple(LCM)
• 1.) 4 and 8 LCM=
• 2.) 12 and 18 LCM=