1. Significant Figures

2. Significant figures
All digits in a measurement that are known for certain, plus the first estimated (uncertain) digit
Sig figs give an indication of the degree of precision for a measurement and/or calculation

3. Sig Fig rules – KNOW AND USE THEM
Rules for determining how many sig figs are in a measurement:
All non-zero values ARE significant
i.e. 54 mm has 2 sig figs
5400 m has 2 sig figs
All zeros between non-zero digits ARE significant
i.e. 504 N has 3 sig figs
For numbers less than 1
Zeros directly after the decimal point are not significant
i.e J has 3 sig figs

4. Sig Fig rules – KNOW AND USE THEM
Rules for determining how many sig figs are in a measurement: ctd
A zero to the right of a decimal AND following a non-zero digit IS significant
0.150 m has 3 s.f.
15.0 kg has 3 s.f.
All other zeros are NOT significant

5. Scientific Notation & Sig Figs
Use scientific notation when you need to specify how many zeros are significant:
i.e. write 1500 N with 3 s.f.
The best way to do this is with scientific notation: 1.50 x 103 N
Write kg with 4 s.f.

6. Sig figs in problems
Many problems will have values that look like they only have 1 s.f.
Assume that all digits in the problems are significant
i.e. if a problem says that and object has a mass of 100 kg, please treat that as 3 s.f.

7. Sig. Figs in calculations
When adding/subtracting:
Your answer must have the same degree of precision as the least precise measurement (choose the smallest number of decimal places)
i.e.: 24.2 g g g = g →31.8 g
When multiplying/dividing:
The number of sig figs in the answer is equal to the least number of sig figs in any of the measurements used in the calculation
i.e.: 3.22 cm x cm x 1.8 cm = cm3 → 72 cm3

8. How many sig figs in each of the following?
Examples/ Homework
How many sig figs in each of the following?
415.2 cm s
1500 g W cm cm s
35000 kg
1.25 cm cm cm cm
2.32 mL mL mL mL
36.5 g g g
5.85 kg x kg x 7.3 kg
25.50 m x m x 0.095m
25.32 mL x 6.87 mL x 35.7 mL

9. Metric Conversions

10. Converting in the Metric System
Larger prefix – decimal moves left Smaller Prefix – decimal moves right 1 mi = .62 km 1 kg = 2.2 lbs 1 mL = 1 cm3 See handout – Copy into notebook/notes

11. Practice
Convert 75 mL to cm3 Convert 350 mL to L Convert 500 m to Km Convert Kg to g Convert 5.0 x 103 mL to L Convert 100 mL to L Convert 600 Kg to g Which two of these are equivalent lengths? 60 mm m 6000 cm Km In metric, the base unit for length is the ______. In the metric system, the base unit for mass is the ______. The measure of the amount of 3-D space that an object occupies is known as ________. Which of the following are equivalent lengths? 450 cm 45,000 mm 45 m 45,000 Km
Which of these is the shortest length?
60 mm Km
0.600 m 6000 cm
Which of the following is the largest mass?
1000 mg 5 Kg
800 cg 100 g
Which metric distance is equal to 0.62 miles?
1 mm 1 cm
1 Km 1 m
Which of the following conversions is/are incorrect?
1 Km = 1000 m 1 m = 1000 mm
500 cm = 0.5 m 100 mm = 1 cm
Which of the following metric masses is approximately equal to 2.2 pounds?
1 mg 1 Kg
1 µg 1 g 
How many millimeters are in one kilometer?
How many milliliters are in one deciliter?