Get formatted byte size from long value

gistfile1.cs

public static string FriendlyFileSize( long size) {
    const double @base = 1024d;
    const string format = "{0:0.#} {1}";
	
    if (size == 0L) {
        return "0 b";
    } 

    var magnitudes = new Dictionary<int, string> {
        {0, "B" }, {1, "kB"}, {2, "MB"}, 
	{3, "GB"}, {4, "TB"}, {5, "PB"}, 
	{6, "EB"}, {7, "ZB"}, {8, "YB"}
    };

    var magnitude = Math.Min(8, (int) Math.Log(size, @base) );
    var divider = Math.Pow(@base, magnitude);

    var value = size/divider;

    return string.Format(format, value, magnitudes[magnitude]);
}