2. Significant Figures
Notes on PAGE _____

3. 7.21 cm Significant Figures
All of the known digits + 1 estimated digit
7.21 cm

4. Rule #1 All non-zero numbers are significant (numbers 1-9)
3.89 = __significant figures
938.3 = ___ significant figures 3 4

5. Rule #2 Sandwich rule: all zero’s between non- zero are significant
202 = __ significant figures 3

6. Examples Rule #2 8 6 67000045 = __ significant figures

7. Rule #3
Leading zeros are NOT significant (zeros at the front of a 1-9 number)
EVEN WITH A DECIMAL

8. Examples Rule #3 2 2 0.0098 = ___ significant figures

9. Rule #4
Trailing (after) zeros are only significant WITH A DECIMAL in the number
= __significant figures 5

10. Practice the zero rules :4
1000. = ___ sig figs
45000 = ___ sig figs
= ___ sig figs
= ___ sig figs 2 6 7

11. Practice the zero rules:6
= __sig digs
9800 = __ sig digs
= ___sig digs 2 4

12. Significant Figures
Lets get a better understanding 

13. Rule #5
Numbers obtained through counting or are defined have unlimited significant figures
60 minutes = 1 hour
24 people

14. Rounding Sig Figs
Look at the digit to the right of the one you need to round.
If is is < 5 – leave it alone
If it is  5 – round up
m = _____ (4 sig figs)
56.31 m

15. Rounding 0.001775 m = ___________ (2 sig figs) 0.0018 m

16. 46.352
Round the number to 3 significant figures.
46.4
46.4

17. 46.352
Round the number to one significant figure. 50 50

18. 46.352
Round the number to two significant figures. 46 46

19. Multiplication and Division
The answer should be rounded to the same number of significant figures as the least number of significant figures in the calculation

20. Examples 6.4 m2 60 cm2 0.003483 cm2 4.56m x 1.4m = 5cm x 11cm =
in x 19.35in =
60 cm2
cm2

21. Sig Fig Practice #1 1.0070 m  5 sig figs 17.10 kg  4 sig figs
How many significant figures in each of the following?
m 
5 sig figs
17.10 kg 
4 sig figs
100,890 L 
5 sig figs
3.29 x 103 s 
3 sig figs
cm 
2 sig figs
3,200,000 
2 sig figs