Validation of Turkish Identification Number

validator.js

/*
** Properties of Turkish Identification Number
* Every Turkish citizen has unique one of it.
* It must consist of eleven digits.
* Last digit must be even.
* First digit cannot be zero.
* The sum of first, third, fifth, seventh and
  nineth digits is multiplied by seven. The sum
  of second, fourth, sixth and eighth digits is
  substracted from it. When that number is 
  divided by ten, the remainder must be equal 
  to tenth digit.
* When the sum of the first ten digits is divided
  by ten, the remainder must be equal to eleventh
  digit.
* When number 29999 is substracted from first nine
  digits, identification number of previous person
  can be found.
*/

function checkNumber(number) {
    var result = true;
    var numbers = [];

    while (number) {
        numbers.push(number % 10);
        number = Math.floor(number / 10);
    }

    numbers.reverse();

    var length = numbers.length;
    if (length != 11)
        result = false;

    var eleventhNumber = numbers[(length - 1)];
    if (eleventhNumber % 2 != 0)
        result = false;

    var firstNumber = numbers[0];
    if (firstNumber == 0)
        result = false;

    var sumOfOddNumbers = numbers[0] + numbers[2] + numbers[4] + numbers[6] + numbers[8];
    var sumOfEvenNumbers = numbers[1] + numbers[3] + numbers[5] + numbers[7];
    var guessNumberForTenthNumber = (((sumOfOddNumbers * 7) - sumOfEvenNumbers) % 10);

    var tenthNumber = numbers[9];
    if (tenthNumber != guessNumberForTenthNumber)
        result = false;

    var guessNumberForEleventhNumber = ((sumOfOddNumbers + sumOfEvenNumbers + tenthNumber) % 10);

    if (eleventhNumber != guessNumberForEleventhNumber)
        result = false;

    return result;
}