Stressfree

1   weight 6 ping pongs with another 6 ping pongs. see which side is heavier公仔箱論壇% X, K3 Y: h9 H) b$ w4 R9 r6 O  X
2   spilt the heavier side ping pongs in half and weight against each othertvb now,tvbnow,bttvb: c  x# [( j% Z$ G8 u6 h, y& o
3   weiht either ping pongs one on one then you will know which is the heavy one.