id	title	challengeType	forumTopicId	dashedName
5900f4e01000cf542c50fff2	Problem 371: Licence plates	5	302033	problem-371-licence-plates

--description--

Oregon licence plates consist of three letters followed by a three digit number (each digit can be from [0..9]).

While driving to work Seth plays the following game:

Whenever the numbers of two licence plates seen on his trip add to 1000 that's a win.

E.g. MIC-012 and HAN-988 is a win and RYU-500 and SET-500 too. (as long as he sees them in the same trip).

Find the expected number of plates he needs to see for a win. Give your answer rounded to 8 decimal places behind the decimal point.

Note: We assume that each licence plate seen is equally likely to have any three digit number on it.

--hints--

euler371() should return 40.66368097.

assert.strictEqual(euler371(), 40.66368097);

function euler371() {

  return true;
}

euler371();

// solution required