1. Metric Base Units Meter (m) – length Kilogram (kg) – mass
Kelvin (K) – temperature
Second (s) – time
Mole (mol) – amount of substance

2. Kilo- (k) – 1000 103 Metric Unit Prefixes Base unit
deci- (d) – /10
centi- (c) /100
milli- (m) /1000
micro- (µ) –

3. Measurements and Significant Digits
When taking measurements, include all the numbers you know for sure and one uncertain, guessed at, number.

4. Significant figures (digits)
-- Used to help indicate the precision of measurements
Measurement # of sig. digits g mm
1.84 s cL km cm cm

5. Calculations with significant figures
Addition and subtraction
Answer should have as few digits to the right of the decimal as the least of what you add or subtract.
Example:
4.13 cm cm cm cm
= cm 
= 11.3 cm

6. Multiplication and division
The answer should only have as many significant digits as the least in what is being multiplied or divided.
Examples:
length = 6.43 km width = km
area = km2
 area = 27.0 km2
mass = g volume = 1.8 mL
density = g/ml
 density = 6.7 g/ml