convert number into roman numeral in csharp

main.cs
public static string ConvertToRoman(int number)
{
    if (number < 1 || number > 3999)
        throw new ArgumentOutOfRangeException("number", "Argument must be between 1 and 3999");

    StringBuilder result = new StringBuilder();

    while (number >= 1000)
    {
        result.Append("M");
        number -= 1000;
    }

    if (number >= 900)
    {
        result.Append("CM");
        number -= 900;
    }

    if (number >= 500)
    {
        result.Append("D");
        number -= 500;
    }

    if (number >= 400)
    {
        result.Append("CD");
        number -= 400;
    }

    while (number >= 100)
    {
        result.Append("C");
        number -= 100;
    }

    if (number >= 90)
    {
        result.Append("XC");
        number -= 90;
    }

    if (number >= 50)
    {
        result.Append("L");
        number -= 50;
    }

    if (number >= 40)
    {
        result.Append("XL");
        number -= 40;
    }

    while (number >= 10)
    {
        result.Append("X");
        number -= 10;
    }

    if (number >= 9)
    {
        result.Append("IX");
        number -= 9;
    }

    if (number >= 5)
    {
        result.Append("V");
        number -= 5;
    }

    if (number >= 4)
    {
        result.Append("IV");
        number -= 4;
    }

    while (number >= 1)
    {
        result.Append("I");
        number -= 1;
    }

    return result.ToString();
}
1392 chars
88 lines

main.cs
int number = 1234;
string roman = ConvertToRoman(number);
Console.WriteLine("{0} = {1}", number, roman);
// Output: 1234 = MCCXXXIV
132 chars
5 lines