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JSS2: MATHEMATICS - 1ST TERM

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  1. Properties of Whole Numbers I | Week 1
    4Topics
    |
    2 Quizzes
  2. Properties of Whole Numbers II | Week 2
    4Topics
    |
    2 Quizzes
  3. Properties of Whole Numbers III | Week 3
    4Topics
    |
    1 Quiz
  4. Indices | Week 4
    2Topics
    |
    1 Quiz
  5. Laws of Indices | Week 5
    5Topics
    |
    1 Quiz
  6. Whole Numbers & Decimal Numbers | Week 6
    4Topics
    |
    1 Quiz
  7. Standard Form | Week 7
    3Topics
    |
    1 Quiz
  8. Significant Figures (S.F) | Week 8
    4Topics
    |
    1 Quiz
  9. Fractions, Ratios, Proportions & Percentages I | Week 9
    6Topics
    |
    1 Quiz
  10. Fractions, Ratios, Proportions & Percentages II | Week 10
    4Topics
    |
    1 Quiz
  11. Fractions, Ratios, Proportions & Percentages III | Week 11
    3Topics
    |
    1 Quiz
  12. Approximation & Estimation | Week 12
    1Topic
    |
    1 Quiz
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Significant figures are non-zero digits but that does not mean that zeroes are not significant. The zeroes in between significant digits are also significant. The first non zero significant figure as you read a number from left is the first significant figure e.g.

1st S.f2nd S.f3rd S.f4th S.f5th S.f6th S.f7th S.f8th S.f
25670052
1st S.f2nd S.f3rd S.f4th S.f
0.0001234

Significant figures show the precision of an answer. When a television newscaster reports that a man has won a ₦2 Million lottery, this has been rounded up to one Significant figure. It rounds to the most important figure in the number. 

Rounding to Significant Figures:

The method of rounding to a significant figure is the same for either big or small numbers. The first significant figure is the first non-zero digit as you read a number from the left.

Steps:

1. Look for the required significant figure digit

2. Draw a vertical line after the place value digit that is required.

3. Look at the next digit

4. If it is 5 or more, increase the previous digit by 1

5. If it is 4 or less, the previous digit remains the same.

6. Fill any spaces to the right of the line with zero, stopping at the decimal/point if there is any.

Example 1

Round the following numbers  correct to (a) 1 s.f (b) 2 s.f (c) 3 s.f

i. 3762

ii. 18.05

iii. 0.0006081

 

Solution i

a. 3 | 762

1st S.f2nd S.f3rd S.f4th S.f
3762

7  is closest to 3 (1st S.F)

7 is a round-up number so we add 1 to 3 which gives 4.

= 4000 to 1 s.f

b. 37|62 = 3800 to 2s.f

1st S.f2nd S.f3rd S.f4th S.f
3762

6  is closest to 7 (2nd S.F)

6 is a round up number so we add 1 to 7 which gives 8.

= 3800 to 2 s.f

c. 376 | 2 = 3760 to 3 s.f

1st S.f2nd S.f3rd S.f4th S.f
3762

2  is closest to 6 (3rd S.F)

2 is a round down number so we add 0

= 3760

 Solution ii

a. 1|8.05 = 20 to 1 s.f

b. 18|.05 = 18 to 2 s.f

c. 18.0 |5 = 18.1 to 3 s.f 

 Solution iii

a. 0.0006 | 081 =0.0006 to 1 s.f

b. 0.00060 | 81 = 0.00061 to 2 s.f

c. 0.000608 | 1 = 0.000608 to 3 s.f

Example 2

Give the following, correct to 

i. 1 s.f

ii. 2 s.f

iii. 3 s.f

iv. 4 s.f

a. 6853

b. 29.56785

Solution a

i. 6853 to 1 s.f

1st S.f2nd S.f3rd S.f4th S.f
6853
Screen Shot 2020 11 23 at 11.34.54 AM

8  is closest to 6 (1st S.F)

8 is a round-up number so we add 1 to 6.

Every other digit after the significant digit becomes zero.

= 7000 to 1 s.f

ii. 6853 to 2 s.f

1st S.f2nd S.f3rd S.f4th S.f
6853
Screen Shot 2020 11 23 at 11.35.47 AM

5  is closest to 8 (2nd S.F)

5 is a round up number so we add 1 to 8.

Every other digit after the significant digit becomes zero.

= 6900 to 2 s.f

iii. 6853 to 3 s.f

1st S.f2nd S.f3rd S.f4th S.f
6853
Screen Shot 2020 11 23 at 11.49.33 AM

3 is a round up number so we add 0

= 6850 to 3 s.f

Solution b

i. 29.56785 to 1 s.f

Screen Shot 2020 11 23 at 11.57.29 AM

= 30 to 1 s.f

ii. 29.56785 to 2 s.f

Screen Shot 2020 11 23 at 11.37.19 AM

= 30 to 2 s.f

iii. 29.56785 to 3 s.f

Screen Shot 2020 11 23 at 11.38.36 AM

= 29.6 to 3 s.f

Example 3

Give 0.006098 to

i. 1 s.f

ii. 2 s.f

iii. 3 s.f

i. 0.006098 to 1 s.f

Screen Shot 2020 11 23 at 12.05.35 PM

= 0.0006 to 1 s.f

ii. 0.006098 to2 s.f

Screen Shot 2020 11 23 at 12.06.13 PM

= 0.0061 to 2 s.f

iii. 0.006098 to 3 s.f

Screen Shot 2020 11 23 at 12.06.57 PM

= 0.00610  to 3 s.f

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