T1_LO9 · lo-yr9-measurement-prefixes
Metric prefixes scale a unit by powers of 10. \textbf{kilo
means 1000 times bigger, \textbf{centi} means 100 times smaller, and \textbf{milli} means 1000 times smaller.}
Steps
Decide whether you are changing to a bigger or smaller unit.
Use powers of 10: metres $\leftrightarrow$ centimetres $\leftrightarrow$ millimetres.
Multiply when changing to a smaller unit.
Divide when changing to a bigger unit.
Key facts
$1 km=1000 m$
$1 m=100 cm$
$1 cm=10 mm$
$1 L=1000 mL$
$1 kg=1000 g$
Going the wrong way with place value. Converting metres to centimetres means multiplying by 100, not dividing by 100.
Convert $3 km$ to metres.
Convert $250 cm$ to metres.
Convert $4 L$ to mL.
Example 1: km to m
Convert $2.5 km$ to metres.$$ 2.5\times1000=2500 m $$
Example 2: cm to m
Convert $450 cm$ to metres.$$ 450\div100=4.5 m $$
Example 3: L to mL
Convert $1.8 L$ to mL.$$ 1.8\times1000=1800 mL $$
Example 4: reasoning
Which is larger: $0.01 km$ or $1000 mm$?$$ 0.01 km=10 m,\quad1000 mm=1 m $$So $0.01 km$ is larger.