A series problem of administrative ability test Sequence: 12,3,4,9,25,3,5,15,36,2,6,) Option: a.13 b.12 c.11 d.10 Explain the sequence law of this problem

A series problem of administrative ability test Sequence: 12,3,4,9,25,3,5,15,36,2,6,) Option: a.13 b.12 c.11 d.10 Explain the sequence law of this problem

How did 3 * 3 = 9 come from upstairs?!
12 * 3 = 4 * 9 25 * 3 = 5 * 15 36 * 2 = 6 * () so () = 12