[lazerpants]

From your source:

So the answer is NO; 24 is a rather gross exaggeration of the number of homes available for sale/rent.

Gotta read the source, not just cite it.

[wu-ikkyu]

Ditto my friend, which is why I used the word "empty" (meaning vacant) rather than "available for sale/rent".

13785000 / 610042 = 22.6

24 empty houses for each homeless American (assuming only the USA) seems like a reasonable estimate, especially since the meme is older than 3 Feb 2012.