- ° : degree (symbol: °) used for degrees of arc / hours / temperature etc.
- ⌀ : diameter (symbol: ⌀) diameter of a conic section is typically defined as any chord which passes through the conic's centre
- µ : micro (symbol: µ) is a prefix in the SI and other systems of units denoting a factor of 10-6 (one millionth)
- № : numero (symbol: №) abbreviation of the word number(s) indicating ordinal numeration
- Ω : ohm (symbol: Ω) is the SI derived unit of electrical resistance