0.4 · Preface · Tools: SI prefixes
Prefixes: kilo to femto
One word in front of a unit that says how big or small.
SL+HLEasier8 minFree
Hook
The distance to school and the width of a virus are both lengths. Do we write them with the same number of zeros? No. We change the prefix.
Follow the arrows
1 / 3
Check 1 of 3
What does the prefix kilo mean?
Check 2 of 3
Which is the longest?
Check 3 of 3
4.2 µm written in metres is…
Apply
A cell is 0.000035 m wide. Write its width using a prefix, and explain your choice.
Your writing is saved on this device.
Remember earlier lessons
From lesson 0.3
How many SI base units are there?
From lesson 0.3
The SI base unit of mass is…
Summary card
Key points
- • A prefix multiplies a unit: 1000 g = 1 kg.
- • High: kilo 10³, mega 10⁶, giga 10⁹, tera 10¹², peta 10¹⁵.
- • Low: milli 10⁻³, micro 10⁻⁶, nano 10⁻⁹, pico 10⁻¹², femto 10⁻¹⁵.
Formulas
- 1 km = 10³ m
- 1 µm = 10⁻⁶ m
Key terms
- Prefix :
- a word in front of a unit that multiplies it by a power of ten
Common errors
- • Mixing up M (mega) and m (milli).
- • Getting the sign of the exponent wrong.
Checks solved: 0 of 3