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. |