1. Significant Figures

2. What are “sig figs”? Measured values!
Precision = how finely tuned your measurements are
Accuracy = how close your measurement is to the accepted value
The precision of a measurement depends on the tool used to make it

3. You need to measure out 200 milliliters of tap water
You need to measure out 200 milliliters of tap water. You might think you using the beaker with the mark saying "200 mL" would be the way to do it. However, notice it says + or - 5%. 5% of 200 mL is 10 mL. That's a big error. Using the graduated cylinder, you can measure at least to the closest 1 mL. So filling up the 100 mL graduated cylinder twice is only 2 mL error, at most.

4. How long is this leaf?

5. How long is this leaf?

6. When reading instruments
Estimate one place beyond the smallest division on the instrument.
If the instrument is marked to the ones place, estimate the tenths place.
If the instrument is marked to the tenths place, estimate the hundredths place!

7. Place values

8. Rules Non-zero digits ARE significant! Measurement
No. of Significant Figures
234 m
1,678 m
0.23

9. Rules 2. Zeros between non-zero digits ARE significant Measurement
No. Significant Figures
202 mm
1003 cm m

10. Rules
3. Zeros to the right of a non-zero are NOT significant unless specified with a line over the last significant zero OR followed by a decimal
Measurement
No. Significant Figures
200 cm
109,000 m
1,000,000 mm
200. cm
300 cm

11. RULES
4. Zeros to the right of a decimal point but to the left of a non-zero digit are NOT significant
Measurement
No. Significant Figures m g L

12. Rules
5. All zeros to the right of a decimal point and following a non-zero digit are significant.
Measurement
No. Significant Figures
20.00 g mm cm

13. So, remember…
When it comes to zeroes: LEADING – NEVER! CAPTIVE – ALWAYS! TRAILING – MAYBE!

14. Adding and subtracting
All measurements must be in the same units (kilograms, meters, degrees Celsius, etc)
The sum or difference may have no more decimal places than the least number of decimal places in the problem.
11.44 g g g g = ? 2.34 m m + 24 m = ?

15. Multiplying and Dividing
0.304 cm x cm = ? g ÷ 8.50 g = ?
1. All measurements must be in the same units 2. The number of significant figures should equal the least number of significant figures in the problem.

16. Individual Practice How many sig figs? 9000.0 25.098 0.0003 0.00300
230007
2000
Complete the following:
= ?
0.304 x = ?
What does the calculator display?
What is your answer?

17. Answers How many sig figs? 9000.0 = 5 25.098 = 5 0.0003 = 1
= 3
= 6
= 6
2000 = 1
Complete the following:
= 19.4
0.304 x = 22.4