Journals Library

Use of numbers

Use of numbers


Ages should be written in full from one to ten and as numerals for 11 upwards. For example: over 40, under nine.

Always use numerals and hyphens for the adjectival form, e.g. ‘8-year-old child’ or ‘80-year-old woman’.

Equation numbering

Please number all equations in your report in the following format, aligned to the right of the equation. For example:

S= −2.59N2+8.74N+90.07                                                                                      (1)

Numbers, units and dates

Numbers in the text should usually be written in full from one to ten and as numerals for 11 upwards.

Ordinal numbers up to and including nine in full, thereafter numerals, e.g. 21st.

However, numerals may be used for numbers less than ten if presented in parentheses, and numbers at the beginning of a sentence should always be written in full.

Numbers followed by units should always be presented as numerals.

Units of time not abbreviated: years, months, weeks, days, hours, minutes, seconds.

Compound units separated by a solidus: kg/m2, ml (not mL).


Per cent should normally be written in full; however, if this appears several times within a paragraph it is acceptable to use the % symbol.

The % symbol should always be used in mathematical and statistical contexts, tables and lists.

The % symbol must always be associated with a numeral, e.g. 7% not seven %.

Units of measurement

Units must always be use Si or SI-derived units.