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

Kilo- (k) – 1000 103 Metric Unit Prefixes Base unit deci- (d) – 0.1 1/10 centi- (c) - 0.01 1/100 milli- (m) - 0.001 1/1000 micro- (µ) – 0.000001 10-6

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

Significant figures (digits) -- Used to help indicate the precision of measurements Measurement # of sig. digits 142.04 g 5 0.0021 mm 2 1.84 s 3 0.6240 cL 4 87.3010 km 6 0.000302 cm 3 4.02000 cm3 6

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 + 2.1435 cm + 1.1 cm + 3.901 cm = 11.2745 cm  = 11.3 cm

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 = 4.2040 km area = 27.03172 km2  area = 27.0 km2 mass = 12.04 g volume = 1.8 mL density = 6.688888888 g/ml  density = 6.7 g/ml