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JSS3: MATHEMATICS - 1ST TERM

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  1. Binary Number System I | Week 1
    5Topics
    |
    1 Quiz
  2. Binary Number System II | Week 2
    6Topics
    |
    1 Quiz
  3. Word Problems I | Week 3
    4Topics
    |
    1 Quiz
  4. Word Problems with Fractions II | Week 4
    1Topic
    |
    1 Quiz
  5. Factorisation I | Week 5
    4Topics
    |
    1 Quiz
  6. Factorisation II | Week 6
    3Topics
    |
    1 Quiz
  7. Factorisation III | Week 7
    3Topics
    |
    1 Quiz
  8. Substitution & Change of Subject of Formulae | Week 8
    2Topics
    |
    1 Quiz
  9. Simple Equations Involving Fractions | Week 9
    3Topics
    |
    1 Quiz
  10. Word Problems | Week 10
    1Topic
    |
    1 Quiz
Lesson 3, Topic 1
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Sum & Difference

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Sum:

The sum of two or more numbers is the result obtained when they are added together.

For example: The sum of 18, 22, and 160 is 

18 + 22 + 160 =  200

 Difference:

The difference between two numbers is the result obtained when one of the numbers is subtracted from the other.

Positive difference: Larger number – Smaller No

Negative difference: Smaller No – Larger No

Example 1

Find the sum of the following

a. 89 and 98 = 187

b. -75 and 105 = 105 -75 = 30

c. -6.8 and -7.5

= -6.8 – 7.5 = -14.3

d. -7, -89 and 56

56 – 7 – 89 

56 – 96 = -40

Example 2

Add 15.5  to the positive difference between  43.6 and 27.8

Screen Shot 2020 11 24 at 12.27.00 PM

Example 3

Add 18 to the negative difference between 56 and 45

45 – 56 =  -11

18 + – 11

=  18 – 11

= 7

Example 4

From the sum of 78 and 129 subtract 264 

Screen Shot 2020 11 24 at 12.29.23 PM

Example 5

The sum of a certain number and 18 is 40.  Find the number.

Let  the certain number be X

X + 18 = 40

= 40 – 18

= 22

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