Is this correct, please?

an orbital period of the order of several thousands of days


This is a binary star system with an orbital period of the order of several thousands of days.

I'm interested in knowing if the prepositions are appropriate.

  • 1
    Please give a full sentence and state what your particular query is. Proofreading is not a service offered by this site.
    – fev
    Jul 22, 2021 at 13:43

1 Answer 1


As a scientist, I would express an uncertain number within a ten-fold range, as either “several” or “the order of”, but never both. As they express the same idea (differing only in the greater precision of “order of”) if both were used one would always be superfluous. So it’s:

“…a period of several thousand days”


“…a period of the order of a thousand days” (British English)

“…a period on the order of a thousand days” (American English)

The latter pair would, I think, sound unnatural outside a technical context.

  • 1
    A more general usage is on the order of X. It refers to orders of magnitude, i.e, x, 10x, 100x, .... To say something is on the order of X means it's more than 1/10 X and less than 10X, in whatever dimension you're measuring. If you're not measuring, then it's metaphorical and not exact. Jul 22, 2021 at 18:36
  • 1
    @JohnLawler — I know. Isn’t that what I said, or at least implied by “ten-fold range”?
    – David
    Jul 22, 2021 at 18:48
  • 1
    @David No, not exactly. It's on the order of, not of the order of. Only one of. Jul 22, 2021 at 21:35
  • @JohnLawler — I didn't know that, but you are the mathematician, I believe. I'll check for myself tomorrow and correct.
    – David
    Jul 22, 2021 at 23:18
  • 1
    No, I am actually the grammarian. I have a degree in math, but that just lets me speak the language. Jul 23, 2021 at 1:02

Not the answer you're looking for? Browse other questions tagged or ask your own question.