Writing numbers in business documents

Posted on 19 September 2014 by Lucy Gregory

There are so many circumstances in which you write numbers at work that we can’t cover them all here. However, the general principles below (or slight variations) are common to many writing style guides.

Standard rules for writing numbers

Spell out numbers under 10

One country

Four emails

Nine colleagues

Use figures for numbers 10 and above

11 countries

23 emails

451 colleagues

When mixing high and low numbers in one sentence, it can look more consistent to use figures for all numbers

We’re 3 months into our 18-month development programme.

This will depend on the context though.

Exceptions to the standard rules

Write decimals and percentages in figures


0.5 km

Write measurements, dates, times, ages and years in figures

105 metres

5 September

3 pm

5 years old

The year 1986

Write fractions in letters



Write million and billion in letters

12 million inhabitants

Or even

twelve million inhabitants

It is common, although not essential, to write a number at the beginning of a sentence in letters

Forty-three delegates attended the meeting.

Where you have two numbers next to each other, write one of them as letters and the other as figures

This new stunning development features four 2-bed properties, eleven 3-bed properties and five 4-bed properties.

Joe ordered fourteen 5-seater minivans.


Final thought on writing numbers

Sometimes figures have more impact than letters, so you might decide to bend these rules for article headings, brochures and other marketing material.

For example: 5 top tips for writing the perfect email

Just make sure you’re consistent throughout your documents.