An Approximation

It would be appropriate in Popular Science but not in Nature.

It depends on both the content of the sentence (would a difference of 250,000 years make a significant difference on whatever timescale the event is usually measured by?) and the context of the sentence (is the audience just your average person, or is this intended to be a technical article?).

Oh, I'm talking about in terms of just a novel. Another example would be saying the Big Bang happened approximately fourteen billions years ago, rather than 13.75 billion years ago, since I want to write it out in actual words. I just didn't want to abuse the word "approximately," so if it's okay in Popular Science, then that's my answer.

Thanks.

Honestly if you're just writing a novel, I wouldn't even bother using qualifiers like "about" or "approximately" unless whoever is speaking is supposed to be an expert on the subject.

But if you don't use those qualifiers, doesn't it become downright wrong? In the case I'm speaking of, it's in the narration.

It's really up to you because I don't know what tone you're going for, but (again, depending on context) it's sometimes better to be precisely wrong than to be vaguely right.

Why not say 'nearly 14 billion years ago'?

'About' or 'approximately' could mean more than that, and as far as I am aware that would definitely be wrong.

Rover

Good point, Rover. But, then again, science, in refining itself, could discover in the future that it's actually a tad bit more than 14 billion, for example, 14.25 billion. Who knows? It could even go down to 13.5. Or maybe 13.75 is as accurate as it'll ever be. I don't know. It's science.

Four billion and fourteen billion are already approximations. No qualifier is needed, but you can use one if you like. It's like saying "an hour ago"—you don't mean 60.0 minutes.

Good point, sir!