How to Write Numbers

Photo by Mika Baumeister on Unsplash

Surely, everyone knows how to write numbers, so why write an article about writing numbers? If you are only writing for your country or region, you won't need to read this article. However, I hope you will find this article helpful if you are writing for a global audience.

Decimal Separator

The decimal separator separates the whole number from the decimal fraction of a number. The decimal separator varies around the world by country and region. The most common decimal separators are the period (full stop) and the comma.

The period is the decimal separator in most English-speaking countries, including the United States, Canada, and Australia.

The comma is the decimal separator in many European countries, including Germany, France, Spain, Italy and the Netherlands.

In some countries, such as India and South Africa, the period and the comma are used as decimal separators depending on the context.

It's important to note that different conventions can confuse when communicating numbers between countries. To avoid ambiguity, it's often helpful to specify the decimal separator explicitly by using '0.5' instead of '.5' or '0,5' instead of ',5'.

Thousands Separator

Countries which use the period as the decimal separator use the comma as the thousands separator

The comma separates groups of three digits in the whole number. For example, "One thousand, two hundred and thirty-four" is written as "1,234.56" in the United States and the United Kingdom.

Countries which use the comma as the decimal separator use the period as the thousands separator.

The period separates groups of three digits in the whole number. For example, "One thousand, two hundred and thirty-four" is written as "1.234,56" in Germany, France, Spain, Italy and the Netherlands.

Some Formatting Suggestions

As you can see, there is no international standard for number formatting, but there are some things you can do to reduce ambiguity.

With larger numbers, you can avoid using a decimal separator by rounding the number up or down.

For whole numbers from 1000 to 9999, you can leave out the thousands separator without reducing clarity. Once you get to 10000 and above, reading the numbers becomes difficult — as in 100000. One approach used in book publishing is to use spaces as separators, as in "100 000".