Anyone know a better method of accomplishing this task?

[Cassandra]

  
internal protected DATATYPE Add<DATATYPE>(DATATYPE item1, DATATYPE item2)  
        { 
            return (item1 is string) && (item2 is string) ? (DATATYPE)Convert.ChangeType((item1.ToString() + item2.ToString()), typeof(DATATYPE)) : (DATATYPE)Convert.ChangeType((Convert.ToInt32(item1) + Convert.ToInt32(item2)), typeof(DATATYPE)); 
        } 
  

I will be glad if you know a better way cause I think there are better ways.