With most abbreviated units of measurement, insert a non-breaking space between the number and the unit so that these never become separated at line breaks. To do this in a Word document, first write the number and the unit all together (e.g.,
5cm,
47km) and then position your cursor between the number and the unit (
5|cm and
47|km) and press
Control+
Shift+
Space. To do this in an HTML document, insert the entity
in that same position.
 | 5 cm |
|  | 20 kg |
|  | 960 Hz |
|
| |
 |
214 km |
|  | 5.5 g |
| |
However, with percentages and temperatures, close up the space between the number and the symbol.
 | 55% |
 | 4.6% |
 | 33°C |
 | 91.4°F |