Knowing when to hyphenate numbers is important because the correct use of the hyphen helps your reader to understand which numbers are part of a given adjective and avoids any ambiguity.
Let’s look at the example on the left.
Is the guy working twenty shifts that are each four hours long, twenty-four shifts that are each an hour long? Or shifts that last twenty-four hours in total?
As you can see, where you place the hyphen in the number can make a significant difference to the meaning of the sentence.
