Form 1 Mathematics Chapter 1 Directed Numbers Form 1 Mathematics Chapter 1

Extra Tutorial List Marks in Open Book Quiz < 30 and Marks in Close Book Quiz < 30 9 students Class numbers: 1, 7, 12, 14, 16, 17, 19, 24, 31 If any student wants to join, please talk to me privately. (Now, 4 students) Every Tuesday CTPs (Last Lesson)

Introduction to Directed Numbers Numbers have two parts: Size or Magnitude Sign or Direction In the figure: – 4 F

Examples of Directed Numbers What does the negative mean? Money in bank: +$1,100 – $950 Students in class (36 students in class) Mon: – 2; Tue: – 1; Wed: 0; Thu: – 3; Fri:0 World time: Sydney: +2; Rome: – 6; London: – 8; New York: – 13 Stairs in the building (up is “+”): Go up 3 steps: +3; Go down 4 steps: – 4

The Four Basic Operations Addition: 3 + 7 Say “3 plus 7” or “The sum of 3 and 7” or “Add 3 to 7” Subtraction: 3 – 7 Say “3 minus 7” or “The difference of 3 and 7” or “Subtract 7 from 3” Multiplication: 3 × 7 Say “3 times 7” or “The product of 3 and 7” or “Multiply 3 and 7” Division: 3 ÷ 7 Say “3 divided by 7” or “The quotient of 3 and 7” or “Divide 3 by 7”

Rules to Remember (p.50) ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( – ) = ( – ) ( – ) ( + ) = ( – ) 正正得正 負負得正 正負得負 負正得負

Addition and Subtraction +3 + (+9) = 3 + 9 ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( – ) = ( – ) ( – ) ( + ) = ( – ) = 12 –7 + (+12) = –7 + 12 = 5

Addition and Subtraction +3 + (– 9) = 3 – 9 ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( – ) = ( – ) ( – ) ( + ) = ( – ) = – 6 7 – (+12) = 7 – 12 = – 5

Addition and Subtraction – 6 + (– 7) = – 6 – 7 ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( – ) = ( – ) ( – ) ( + ) = ( – ) = – 13 – 3 – (+3) = – 3 – 3 = – 6

Addition and Subtraction 7 – (– 7) = 7 + 7 ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( – ) = ( – ) ( – ) ( + ) = ( – ) = 14 – 3 – (–3) = – 3 + 3 = 0

Rules to Remember (p.50) ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( – ) = ( – ) ( – ) ( + ) = ( – ) 正正得正 負負得正 正負得負 負正得負

Multiplication 3  4 = 12 2  4 = 8 1  4 = 4 0  4 = 0 – 1  4 = ? 3  4 = 12 2  4 = 8 1  4 = 4 0  4 = 0 – 1  4 = ? – 2  4 = ? ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( – ) = ( – ) ( – ) ( + ) = ( – ) – 4 – 8

Multiplication 3  (– 5) = – 15 2  (– 5) = – 10 1  (– 5) = – 5 3  (– 5) = – 15 2  (– 5) = – 10 1  (– 5) = – 5 0  (– 5) = 0 – 1  (– 5) = ? – 2  (– 5) = ? ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( – ) = ( – ) ( – ) ( + ) = ( – ) 5 10

Multiplication (+ 7)  (+ 7) = 7  7 = 49 (– 8)  3 = – 8  3 = – 24 = 7  7 ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( – ) = ( – ) ( – ) ( + ) = ( – ) = 49 (– 8)  3 = – 8  3 = – 24 Same as (– 8) + (– 8) + (– 8) = (– 24)

Multiplication 4  (– 2) = – (4  2) = – 8 (– 8)  (– 7) = + (8  7) = – (4  2) ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( – ) = ( – ) ( – ) ( + ) = ( – ) = – 8 (– 8)  (– 7) = + (8  7) = 56 Note: (– 8)  (– 7) = (– 8) (– 7)

Time for Practice Page 56 of Textbook 1A Page 62 of Textbook 1A Class Practice Page 62 of Textbook 1A Questions 1 – 2

Rules to Remember (p.50) ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( – ) = ( – ) ( – ) ( + ) = ( – ) 正正得正 負負得正 正負得負 負正得負

Division (+ 7)  (+ 7) = 7  7 = 1 (– 9)  3 = – 9  3 = – 3 = 7  7 ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( – ) = ( – ) ( – ) ( + ) = ( – ) = 1 (– 9)  3 = – 9  3 = – 3 Note: (– 9) = (– 3) + (– 3) + (– 3)

Division 4  (– 2) = – (4  2) = – 2 (– 12)  (– 6) = + (12  6) = 2 = – (4  2) ( + ) ( + ) = ( + ) ( – ) ( – ) = ( + ) ( + ) ( – ) = ( – ) ( – ) ( + ) = ( – ) = – 2 (– 12)  (– 6) = + (12  6) = 2

Time for Practice Page 59 of Textbook 1A Page 62 of Textbook 1A Class Practice Page 62 of Textbook 1A Questions 3 – 4

Reminder Extra Tutorial Standard Homework (II) 9 Oct (Tue) 9 students (Must) + 4 students (Voluntary) Standard Homework (II) 10 Oct (Wed) Open Book Quiz (Chapter 1) Close Book Quiz (Chapter 1) 17 Oct (Wed)

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