A Bit on Numbering

Q:

Dear Grammer Cop,

A quick question of which is more correct in a scientific manuscript: sevenfold or seven-fold, and does it make a difference if numbers higher than ten are used (e.g. 17-fold?).

Thank you for your time.

--Rick

A:

Dear Rick,

I use the Oxford English Dictionary as the final arbiter in matters like this, and it spells it as one word—sevenfold. The OED stops at twelve, giving no advice for higher numbers, indicating to me that they have no context in historical English.

Higher numbers should be used sparingly, if at all, in my opinion, but I would spell them numerically, and I would use a hyphen. When the phrasing is awkward, I'd rewrite the sentence.

In technical papers, numbers are generally spelled up to ten, then written numerically (with some exceptions for consistency). For example, a list of numbers including large and small numbers should not be spelled out. Also, round numbers are often spelled out, such as a thousand, a million, etc.

Examples for technical and business style:

sevenfold
twelvefold
13-fold
110-fold
102,540-fold – rewrite
He had ten papers due in three classes.
There are a thousand cars in the parking lot.
I have 115 miles to go.
Please get me items 1,5,23,110 and 90.

Hope this helps!