The beast of the number

DCLXVI: simple, no?

If my long-unplayed Iron Maiden album is to be believed, the Number of the Beast is 666. That number is a lot more catchy than when this piece of superstition was first cooked up, when the Beast’s number was DCLXVI.

Without Arabic numerals, mathematics would still be in the Dark Ages. However, writers need to be extremely careful when using them in prose, and there is a very good reason for this: readers do not understand numbers.

“Hang on,” I hear you say, “I understand numbers perfectly well.” Yes, you do, and so do I and so do our readers, when we are doing mathematics. Working out offers in the supermarket, checking your payslip or calculating what 20 degrees Celsius is in Fahrenheit are all works of mathematics. Reading prose, however, is a completely different activity and our minds work in different ways. One of my many aphorisms when I was a magazine editor was, “Don’t give me facts, tell me a story.”

If I read a sentence saying, “Rates moved from $21,834 per day to $21,688,” I seldom comprehend whether rates have gone up or down. I need to read it a second time, after I have subconsciously switched my brain from ‘narrative mode’ to ‘data mode’.

Anyone who has ever driven on icy roads knows the feeling: even when the car is going straight, it loses traction as it passes over a patch of ice. The brain does the same thing when it encounters numerals in prose: the brain loses traction. To the casual reader, a rate rise of 28% looks very much like a rise of 82%. To say rates rose by a quarter or nearly doubled is less precise, but actually conveys more meaning.

It’s hard to eliminate numbers from your writing entirely, especially if your job is to analyse markets. So there’s no way to remove the numbers from this sentence, as seen in a report I edited today:

Natural gas prices fell from a high of $13.53/MMBtu in October 2005 to a low of $3.31/MMBtu (in August 2009), before recovering slightly to $4.24/MMBtu in April 2011.

At least the writer has done almost everything he can for the reader. He has described the change using words. Prices “fell … from … to … recovering slightly”. A reader who doesn’t understand numbers would still get a sense of what had happened. We could improve it by using words to give a sense of how drastically they fell, such as “plunged”, although one has to be careful about using such melodramatic, tabloid language in this sort of writing.

Look at the following sentence, which is not a particularly dreadful example:

On the benchmark TD3 route, average earnings during the quarter plunged by 24.6% to $20,767pd

What, might you ask, does the reader gain from that fraction of a percent? How is his understanding improved by having to process this extra piece of data? If you have to put numbers in, then two significant figures is about as much as the brain can absorb.

This reaches a low point in paragraphs such as the following, which besmirched my computer screen a couple of years ago:

HPH is ranked at the market leader, with a throughput of 66.3 million teu, up from 60.9 million teu in 2006, and a global share of 13.3%. APM Terminals is in second position, with 60.3 million teu (12.1%) followed by PSA with 54.7 million teu (11%), DP World with 43 million teu (8.7%) and COSCO, which moved 27.3 million teu, and has a market share of 5.5%.

This sort of information should only go in a table (if the exact figures are important) or a graph (if the general relationship between the statistics is what matters). Most readers will come away from reading that sentence without learning anything from it, so what was the point of writing it? Littering your prose with abbreviations only helps to make the whole mess unreadable.

Anything that makes a reader stop and read again is a mark of failure, unless they read it twice simply for the pleasure of reading the beauty of your prose. Chances are, you’re not a good enough writer for that to happen. I know I’m not.
Moral: Prose is for telling stories, not delivering data
PS. My apologies for the strange formatting here. If I indent the quotes, Blogger publishes an old draft of the post. Strange creature, Blogger.