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Divide 3 groups first.
9 C% c8 Y8 s. @; K3 t8 `2 ki.e. 4 x 4 x 4.
/ d- s9 B5 `6 G, ]' l- a5.39.217.77:8898Weight any 2 groups [1st]
* X9 U! y$ q( o' n! i5.39.217.77:8898then you will know the heavier ball in which group.
) }3 Z+ T' P6 H0 d5 [Weight any 2 balls in that group [2nd]公仔箱論壇# O& f4 b2 Z/ M  v
then you will know the heavier ball in which 2 balls.
1 O& q2 y) C5 o; m6 w5.39.217.77:8898Repeat again in remainders [3rd]
' X% j) K8 O6 }3 ]公仔箱論壇Got the heavier ball.