What's the origin of this expression?  What kind of number is that?  Just curious.

Thank you,
Archae0pteryx

Okay, we'll make the OED and Brewer's entries the official answer.

From the OED:

"number, n.
...
 27. fig. to get (also take, etc.) a person's number: to have or make
an accurate assessment of a person's true character, motives,
weaknesses, etc. Cf. MEASURE n. 12b."

source: 
Oxford English Dictionary. 2nd ed. Oxford. OED Online.

The earliest usage cited by the OED is from Bleak House (1853). Other
OED examples are listed in this newsgroup post:
http://groups.google.com/groups?hl=en&lr=&selm=adsM2.641%249Y5.3155233%40news.itd.umich.edu


"Brewer's has the expression but no origin.
TO HAVE SOMEONE'S NUMBER - "To understand them closely; to have an
insight into their thoughts, actions, and character." From "Brewer's
Dictionary of Phrase and Fable" revised by Adrian Room
(HarperCollinsPublishers, New York, 1999, Sixteenth Edition)."
http://www.phrases.org.uk/bulletin_board/26/messages/489.html

----------
search strategy:
oed, number
"have someone's number" dictionary

Regards,
juggler

Thanks, Juggler, that's just fine.

Archae0pteryx

Hey Tryx,

This isn't definitive enough for me to post as an answer without your
consent, but the Oxford English Dictionary suggests that this usage is
comparable to the concept of "measure" (as in "taking someone's
measure").  In other words, when, say, a tailor measures someone for a
garment, he determines that person's size or "number."   As such,
getting someone's "number" is a metaphor for assessing that person's
character, motives, etc.


From the OED:

"number, n.
...
 27. fig. to get (also take, etc.) a person's number: to have or make
an accurate assessment of a person's true character, motives,
weaknesses, etc. Cf. MEASURE n. 12b."
 

The earliest usage cited by the OED is from Bleak House (1853). Other
OED examples are listed in this newsgroup post:
http://groups.google.com/groups?hl=en&lr=&selm=adsM2.641%249Y5.3155233%40news.itd.umich.edu



Brewer's Dictionary of Phrase and Fable reportedly lists the phrase
but offers no explanation of its origin.

"Brewer's has the expression but no origin.
TO HAVE SOMEONE'S NUMBER - "To understand them closely; to have an
insight into their thoughts, actions, and character." From "Brewer's
Dictionary of Phrase and Fable" revised by Adrian Room
(HarperCollinsPublishers, New York, 1999, Sixteenth Edition)."
http://www.phrases.org.uk/bulletin_board/26/messages/489.html


Again, though, as the OED suggests, the concept is comparable to
"taking one's measure."

"To take one's measure, to measure one, as for a garment; hence, to
form an opinion of one's disposition, character, ability, etc."
http://dictionary.reference.com/search?q=To%20take%20one's%20measure

Hmmm.  Well, Juggler, if the OED and Brewer's don't know, then I think
it's safe to say we're not going to find out some other way.  So I'll
accept your findings as an answer, with thanks.

This came up this evening when I used the expression at dinner and my
son didn't understand it.  While explaining its meaning, my husband
remarked that he thought it might have to do with telephone numbers,
but I said no way, it was definitely older than that and means
something too different from knowing how to reach someone to have
derived from that.

I have Brewer's on my bookshelf and the OED on the mantel, and shame
on me for not thinking of looking in either one.  So I am paying you
for the reminder I should not have needed:  BOOKS--remember those?

Archae0pteryx

Hi, further to other comments and your husbands remark that it has
something to do with telephone numbers, there is a UK directory
enquiries firm who have recently and very successfully used 'I've got
your number' as a marketing slogan.

http://www.the118118experience.com/

it may require an understanding of british humour to find funny!

the service can be found on 

http://www.118118.com/

The use of the phrase appears to coincide with the growth in organized
sports and the numbering of jerseys. While this is in no way
authoritative, it is reasonable to conclude that it was the result of
a referree or coach informing a player that he is behaving
inappropriately and that they are aware of his conduct.

Tryx,
Thank you for the tip.
-juggler

Generally I'd always understood it meant they knew how tall you were,
for your grave!

Then again, maybe the source of this phrase is the field of dentistry,
where the patient says "I want to be numb," and the dentist looms
above with a syringe full of Novocaine, saying "I've got your number."