1. Ronald Hui Tak Sun Secondary School
Mathematics
Ronald Hui
Tak Sun Secondary School

2. Mathematics Keep silence in the class No talking when I talk
What should be ready in the next lesson?
Textbook
Erasable Pens/Pencils
Notebook & folder
Ronald HUI

3. Factors (p.0.9) Find all factors of 18. 18  1 = 18  1 is a factor
18  4 = 4.5  4 is NOT a factor
18  5 = 3.6  5 is NOT a factor
18  6 = 3  6 is a factor
18  7 = 2…  7 is NOT a factor
Ronald HUI

4. Factors (p.0.9) Find all factors of 18.
18 = 1 x 18
18 = 2 x 9
18 = 3 x 6
18 = 6 x 3
18 = 9 x 2
18 = 18 x 1
Factors of 18: 1, 2, 3, 6, 9, 18
Ronald HUI

5. Factors (p.0.9) Factors of 18: 1, 2, 3, 6, 9, 18
Any number is divisible by 1
1 is a factor of any number
Even numbers are divisible by 2
2 is a factor of any even number
Any number is divisible by itself
Any number is a factor of itself
Ronald HUI

6. Prime Numbers (p.0.9) Prime number (質數) Prime number:
A natural number (other than 1) which is NOT divisible by any number except 1 and itself
Prime number:
2, 3, 5, 7, 11, 13, 17, 19, 23, …
Composite number (合成數)
4, 6, 8, 9, 10, 12, 14, 15, 16, …
1 is not prime nor composite
Ronald HUI

7. Prime Factors (p.0.9) Prime factors (質因子)
A factor which is prime
Factors of 18: 1, 2, 3, 6, 9, 18
Prime factors of 18: 2, 3
All numbers can be expressed as a product of prime factors only – How?
Ronald HUI

8. Index Notation (p.0.10) Factors of 18: 1, 2, 3, 6, 9, 18 18 = 2 x 9
Prime factors of 18: 2, 3
18 = 2 x 9
= 2 x 3 x 3
18 = 2 x  Index Notation
32 = 3 x 3 (指數記數法)
3 is base 底
2 is index 指數
Ronald HUI

9. Index Notation (p.0.10) 32 = 3 x 3 33 = 3 x 3 x 3 34 = 3 x 3 x 3 x 3
3 to the power 2, 3 squared (平方)
33 = 3 x 3 x 3
3 to the power 3, 3 cubed (立方)
34 = 3 x 3 x 3 x 3
35 = 3 x 3 x 3 x 3 x 3
What is 31 ?
31 = 3
Ronald HUI

10. Index Notation (p.0.10)
Index notation is very helpful in long expression of prime factors
432 = 2 x 2 x 2 x 2 x 3 x 3 x 3
= 24 x 33
86400 = 2 x 2 x 2 x 2 x 2 x 2 x 2 x 3 x 3 x 3 x 5 x 5
= 27 x 33 x 52
Ronald HUI

11. Time for Practice Standard Homework 0-B1 PowerPoint files Page 1
Ronald HUI

12. Enjoy the world of Mathematics!
Good Luck!
Enjoy the world of Mathematics!
Ronald HUI