class BaseUtil 
{

    private static var BASE_CHARS:String = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    
    public static function toNumericBase(input:Int, base:Int):String
    {
        var result:String = "";
        while ( input > 0)
        {
            result = BASE_CHARS.charAt(input % base) + result;
            input = Std.int(input / base);
        }
        return result;
    }
    
    public static function toDecimal(input:String, base:Int):Int
    {
        input = input.toUpperCase();
        var i:Int, len:Int;
        i = len = input.length;
        var result:Int = 0;
        
        while (i-- > 0)
        {
            result += Std.int(Math.pow(base, i) * BASE_CHARS.indexOf(input.charAt(len - i - 1)));
        }
        
        return result;
    }
}

Calculates the base x representation of a decimal value and vice versa.