Being human is a study in what some have termed as "beautiful mess". We often strive for perfection and usually fail to achieve it.
And to be completely honest, that's not all bad. "There is no art in perfection. There is no perfection in art." I am a firm believer in this statement. I find it borne out in many things, such as the fact that humans are not perfectly symmetrical. Anything that can be made perfect can be made perfect again. That is mass production, not art. There is nothing inherently WRONG with this either, but it is my take on it.
All of that said, I say this with all the care I can muster for writers as artists: The reader typically doesn't care about precision when it comes to numbers. All they need is reference or something close. Science fiction writers tend to be the worst offenders when it comes to an excessive amount of precision when it comes to numbers. It's almost as if the thought of a rough number when it comes to speed is considered a bad thing by some of them. I (as I'm certain others) find the overly precise numbers jarring and distracting.
This falls back to "being human". Precision is required in some things. Engines are built to thousandths of an inch. But the reality of it is, in the car, the gauge doesn't *really* need numbers because we know that it "should be about there". This kind of thing pervades life. We know when somethings "correct" when it sits inside of arbitrary tolerances that we find through observation. We know that when it gets outside that tolerance something's wrong. There's no precision there, but it works organically, and generally works well.
With that out of the way, let's look at an example that I found online.
I found this with StumbleUpon (and found it interesting enough to continue reading): http://www.cygnuswar.com/2009/10/episode-50-sky-of-memories.html
The paragraph that I'm going to excerpt here is the one that inspired this post. I will qualify all of this with a "I haven't read the rest of the story yet" so I don't know if the specifics really do play into story or not. If they do, I apologize in advance.
She swallowed in that moment, reflexively, and forced her eyes to focus on the Wallace class in the distance. Her rig’s PAT array had picked up Mac’s Slashdriver at 238 kilometers distant, closing in on a full burn of a few km/h over 1800 with the massive bulk of the starship hanging in blue nothingness another handful of kilometers behind him. Her own throttle was notched near half in conventional drive, 1522 km/h. 5, maybe 6 minutes out.
What struck me as strange in this is that the writer recognizes the entire idea behind human "fuzziness" when it comes to numbers. "5, maybe 6 minutes out" and "another handful of kilometers out" suggests this to me.
If the writer understands this, and gets it, why do they use specifics in other places: "238 kilometers distant", "1522 km/h". The blending of the two makes it especially jarring to me.
Were I to suggest a little bit of editing (and far be it from me to do so, as I, while I do write, often do so for my own pleasure, not for someone else to read), I would recommend the following:
She swallowed in that moment, reflexively, and forced her eyes to focus on the Wallace class in the distance. Her rig’s PAT array had picked up Mac’s Slashdriver at just under 250 klicks, closing in on a full burn around 1800 km/h with the massive bulk of the starship hanging in blue nothingness another handful of kilometers behind him. Her own throttle was notched near half in conventional drive, just over 1500 km/h. 5, maybe 6 minutes out.
It reads more organically. Everything flows in a fashion that doesn't jump from incredible precision to fuzziness. The numbers aren't distracting anymore, they're just indications that "one's moving slightly faster than the other, and they're not that far apart at those speeds", which I sincerely believe is what the author is trying to convey. Depending on the audience, the "5, maybe 6 minutes" thing could probably be left out, or replaces with "a handful of minutes at the most". This does get into the more subjective and style elements that are beyond the scope of this small post.
Fantasy writers aren't immune to this either, though they appear to be less inclined to fall into this trap. Age, however, seems to the area they are wont to use overly precise numbers.
When describing age, it is not necessary to use highly precise (or even loosely precise) numbers. Usually, you can get away without using a number at all. "Approaching middle age" is close enough for most people to get that "well, that one's in his thirties or so". "Just entering puberty". "Elderly". "Wizened". These are all great words and phrases that leaves the reader's imagination to work. And isn't that what we all want to do?