What's the Magic Number?
People are often confused when to transcribe a number in written form and when to use numeric form. The most common occurrence is switching from single-digit numbers to double-digit numbers. The next most common dilemma would be dollars and cents. I would say the third most common issue, due simply to its lack of frequency, is a number at the beginning of a sentence.
Single-digit numbers, one through nine, are written out. Then the magic starts when you hit 10, because this is where you switch to numeric form. For single digits, even for whole dollar currency, i.e. nine dollars, you write the number in written form. Any number above nine, 10 and up, is written in numeric form.
Then we have currency. Again, whole dollar amounts below $10 are expressed in written form. Now once you add cents to the currency, that changes things. Dollars and cents amounts are written in currency form, i.e. $2.50 not two dollars and fifty cents. Of course, there is always an exception in English, right? And that brings us to our last occurrence.
Numbers written at the beginning of a sentence, in most cases, are written out. This becomes a judgment call when your numbers become complex. The rule of thumb is if writing the number out makes the number more difficult to read, you switch to numeric form. A few examples would be:
Two dollars and fifty cents
Two hundred fifty million dollars
As you can see, the second number would be extremely long at the beginning of a sentence and can really become more difficult to read than it should be in written form.
So when you're writing your numbers, think of these three major rules. It will likely cover the majority of any circumstance you have. If you happen to have one that doesn't fit neatly into these rules, let the "appeal" of the form you choose be your guide.
By Antoinette Franks, AAERT Certified Electronic Transcriber