put 3 balls on each side, E8 G, s; h6 M2 t
if balance, we can prove that all 6 balls on the 天平 is normal, tvb now,tvbnow,bttvb6 g$ Y8 v& s$ e6 i" Y' T0 L
if not balance, we can prove that the 6 balls outside the 天平 is normal.. [+ N3 K6 G! B3 V& M F' E
then use the proved-normal ball on one side and put the other ball on other side tvb now,tvbnow,bttvb: ^* |( T4 A |& u
to determine the abnormal is heavy and light |