The minus sign

First new entry in more than 8 years! 

Recently, I discovered an important difference between using a hyphen (-) and a minus sign (−) in reports. 

When using a hyphen to indicate a negative number (e.g. because you have copied and pasted a negative number from Excel, and it automatically pastes as a hyphen), and the number is long so it crosses onto the next line of text, the hyphen can be left behind (i.e. the line break can be between the hyphen and the number).

Here is a recent example. The text describes a decrease in emissions that leads to a negative emission, −256,000 tCO₂eq/year. However, in the top text, the hyphen (used here to indicate a negative number) has separated from the rest of the number, and it is easy to misinterpret the text as saying the new figure for emissions is 256,000 tCO₂eq/year. In the lower text, the minus sign has been used, and it automatically carries onto the next line.

In conclusion, it is best to use a minus sign (which can be accessed in Microsoft Word through the insert-symbol function) to indicate negative number, rather than a hyphen. Not only because it is correct and more visually pleasing, but also because it keeps the sign and the number together when there is an automatic line break.