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JSS1: MATHEMATICS - 1ST TERM

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  1. Whole Numbers I | Week 1
    3Topics
    |
    1 Quiz
  2. Whole Numbers II | Week 2
    1Topic
    |
    1 Quiz
  3. Counting in Base Two | Week 3
    4Topics
    |
    1 Quiz
  4. Arithmetic Operations | Week 4
    3Topics
    |
    1 Quiz
  5. Lowest Common Multiple (LCM) | Week 5
    1Topic
    |
    1 Quiz
  6. Highest Common Factor | Week 6
    1Topic
    |
    1 Quiz
  7. Fraction | Week 7
    7Topics
    |
    1 Quiz
  8. Basic Operations with Fractions I | Week 8
    3Topics
    |
    1 Quiz
  9. Basic Operations with Fractions II | Week 9
    1Topic
    |
    1 Quiz
  10. Directed Numbers | Week 10
    3Topics
    |
    1 Quiz
  11. Estimation and Approximation I | Week 11
    3Topics
    |
    1 Quiz
  12. Estimation and Approximation II | Week 12
    6Topics
    |
    1 Quiz
Lesson Progress
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A number such as 270.8143 is an example of a decimal number.

Decimal point e1605977715655

To find the number of decimal places (d.p) simply count the number of figures after the decimal point. Thus, this number has 4 d.p.

decimal place

Example:

a) 47.04 -> 2 d.p

b) 0.395 -> 3 d.p

d.p. means decimal places.

Rounding Off Numbers | Specific Number of Decimal Places:

Sometimes, it is useful to round decimal numbers to a specific number of decimal places or to the nearest whole number.

To round a decimal number to a given number of decimal places:

1. Look for the last digit  (i.e. the required decimal place you are rounding to)

2. Then look at the next digit to the right i.e. the decider.

3. If the decider is 5 or more round up (i.e. add 1 to the last digit) if it is less than 5, then add nothing.

Example:

Give the number 58.07526 correct to:

a. 1 d.p

b. 3 d.p.

Solution a:

1 d.p2 d.p3 d.p4 d.p5.dp
58.07526

The number that represents 1 d.p in this example is 0. The next digit to the right the decider) is 7 which is greater than 5. So we add 1 to 0 in this example.

i.e. add 1 to the 1st d.p.  i.e.  0  +  1    =   1

Therefore, 58.07526 = 58.1  correct to 1 d.p.

Solution b:

1 d.p2 d.p3 d.p4 d.p5 d.p
58.07526

The number that represents 3 d.p in this example is 5. The next digit to the right the decider) is 2 which is less than 5. So we add nothing.

Therefore, 58.07526 = 58.075 to 3 d.p

Now try this for yourself

Example: Give the number 0.0164

Correct to:

a. 2 decimal places

b. 3 decimal places

Solution

a. 0.0164   =   0.02   correct to 2 d.p

b. 0.0164    =   0.016 correct to 3 d.p

Awesome!

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