1. divide 6 and 6, both sides will not equal 7 v8 o, `% i0 d% ^公仔箱論壇2. take any side of the 6, divide then 3 and 3, again both sides will not equal 7 _# u( A" z! }/ x- ]1 r3. take any 2 and weigh them , \5 G* B, @+ o6 A7 n+ lif they equal, the one left is the ball.