Please see my solution to the problem. I think it works for such large numbers.

Ugh. And Ruby just crossed the 500 barrier.

Yeah, you are right: it should indeed.

Seems like it should be to me? It's what I get running it through my solution as well as the test solution. (19999999 -> 91999999).

Moot point though I guess since JS tests can't be changed anyway.

No, it should not: think again.

That's a bad test case. It should be Test.assertEquals(nextBigger(19999999),91999999)

Sadly, with 500+ solutions one cannot change the testing suite any longer :(

I suggest adding values like 19999999 to avoid some brute-force approaches, e.g.:

Test.it("Bigger numbers",function(){
  Test.assertEquals(nextBigger(19999999),99999991)
  //...
})

Run it with 19999999 and crack some eggs on your macbook because this baby's gonna get pretty hot!

(actually skip one 9 as this one takes ca. 70sec on my machine)

Seems like the perfomance impact is exponential for cases like this (someone correct me if I'm wrong here).