1. Review of Significant Figures

2. Rules for Significant figures Rule #1
All non zero digits are ALWAYS significant
How many significant digits are in the following numbers?
3 Significant Figures
5 Significant Digits
4 Significant Figures
274
25.632
8.987

3. Rule #2 All zeros between significant digits are ALWAYS significant
How many significant digits are in the following numbers?
3 Significant Figures
5 Significant Digits
4 Significant Figures
504
60002
9.077

4. Rule #3 All FINAL zeros ARE significant if a decimal point is present
How many significant digits are in the following numbers?
32.0
3 Significant Figures
6 Significant Digits
7 Significant Figures

5. Rule #4 Zeros at the end are NOT significant if no decimal is present
200 cm 1 sig fig
150 m 2 sig figs

6. Rule # 5 Zeros at the beginning (Leading Zeros)
Are NEVER significant..

7. For example 1 Significant Digit 0.0002 3 Significant Digits
How many significant digits are in the following numbers?
1 Significant Digit
3 Significant Digits
6 Significant Digits
2 Significant Digits
0.0002
6.02 x 1023
150000
800

8. Rule # 6
All counting numbers and constants have an infinite number of significant digits
For example:
1 hour = 60 minutes
12 inches = 1 foot
24 hours = 1 day

9. How many significant digits are in the following numbers?
0.0073
2500
7.90 x 10-3
670.0
18.84
2 Significant Digits
6 Significant Digits
3 Significant Digits
4 Significant Digits
1 Significant Digit

10. More Practice g
20000 L g
6.90 x 105 L g
400. cm

11. Rules Rounding Significant Digits Rule #1
If the digit to the immediate right of the last significant digit is less than 5, do not round up the last significant digit.
Ex. You have the number and you want 3 significant digits
The last number that you want is the 8 –
The number to the right of the 8 is a 2
Therefore, you would not round up & the number would be 43.8

12. Rounding Rule #2
If the digit to the immediate right of the last significant digit is 5 or greater than 5, you round up the last significant figure
Ex round to 4 significant digits
– The number you want is the 8 and the number to the right is a 7
Round up & get 234.9

13. Say you have this number
(want 3 significant digits)
The number to the right of the digit you want is a 5
2.53

14. Let’s try these examples…
(want 3 SF)
(want 2 SF)
(want 3 SF)
(want 1 SF)
(want 2 SF)
201 18
136
0.003 99