http://www.scribd.com/doc/2903780/How-to-find-no-of-structural-isomers- . CHECK THAT LINK. YOU WILL GET TO KNOW AN EASY METHOD TO DO SO.RATE IF USEFUL. I HAVE TRIED BASED ON THIS METHOD AND IS QUITE EASY TO FIND IT AND U WONT MISS ANY ISOMERS IN A QUESTION AND USEFUL FOR INTEGER MATCH TYPE.DONT BLOCK THIS ARITCLE!!!!!