1. Significant Figures

2. Significant Figures
Numbers can be rounded to a given number of significant figures
275300
This is the first significant figure
This is the first significant figure
The first significant figure is the first non-zero number

3. Significant Figures
Numbers can be rounded to a given number of significant figures
275300
This is the second significant figure
This is the second significant figure

4. This is the first significant figure Round up or stay the same?
Significant Figures
Round to 1 significant figure
This is the first significant figure
275,300
Round up or stay the same?
Round up! 3
00,000

5. Mini-Whiteboards
Significant Figures

6. This is the first significant figure
What is the first significant figure?
This is the first significant figure

7. This is the third significant figure
What is the third significant figure?
This is the third significant figure

8. This is the fourth significant figure
What is the fourth significant figure?
302700
This is the fourth significant figure

9. This is the third significant figure
What is the third significant figure?
This is the third significant figure

10. This is the first significant figure
What is the first significant figure?
307482
This is the first significant figure

11. This is the second significant figure Round up or stay the same?
Significant Figures
Round to 2 significant figures
This is the second significant figure
275,300
Round up or stay the same?
Round up! 28
0,000

12. This is the first significant figure Round up or stay the same?
Significant Figures
Round to 1 significant figure
This is the first significant figure
Round up or stay the same?
Stay the same
0.003

13. This is the first significant figure Round up or stay the same?
Significant Figures
Round 36.7 to 1 significant figure
This is the first significant figure
36.7
Round up or stay the same?
Round up! 40 .0

14. This is the second significant figure Round up or stay the same?
Significant Figures
Round 36.7 to 2 significant figures
This is the second significant figure
36.7
Round up or stay the same?
Round up! 37 .0

15. Significant Figures
Number
To 3 s.f.
To 2 s.f.
To 1 s.f.
4213
6435
23.65
43.89
0.0465
0.9649
0.4054
0.4109

16. Significant Figures Number To 3 s.f. To 2 s.f. To 1 s.f. 4213 4210
4200
4000
6435
6440
6400
6000
23.65
23.7 24 20
43.89
43.9 44 40
0.0465
0.047
0.05
0.0092
0.009
0.9649
0.965
0.96 1
0.4054
0.405
0.41
0.4
0.701
0.70
0.07
0.4109
0.411
0.0050
0.005

17. 0.0235 Significant Figures – Can you spot the error?
This is the first significant figure
0.0235

18. Significant Figures – Can you spot the error?
0.769

19. Estimating using Significant Figures
We can use significant figures to quickly estimate answers
Round to 1 sf
Round to 1 sf
45 × 34 50
× 30
=1500

20. Estimating using Significant Figures
Round to 1 sf
𝟑𝟔×𝟐𝟐 𝟐.𝟑𝟕
Round to 1 sf
Round to 1 sf 40
× 20
= 𝟖𝟎𝟎 𝟐
=𝟒𝟎𝟎 2

21. Estimating using Significant Figures
Screws cost £2.90 per packet. How much would 21 packets cost?
Round to 1 sf
Round to 1 sf
£3.00
× 20
= £60