Stressfree

1   weight 6 ping pongs with another 6 ping pongs. see which side is heavier公仔箱論壇9 D! T4 b, ?% g& ?" V0 N
2   spilt the heavier side ping pongs in half and weight against each other
4 i. Y" j  [: P  a2 `7 f3   weiht either ping pongs one on one then you will know which is the heavy one.