Which of the following letter-clusters will replace the

What will come in place of (?) question mark in the given number series.

10, 17, 26, 37, 50, ?

What will come in place of the question mark (?) in the following series?

12, 13, 27, ?, 329, 1646

1 12 31 58 93 ?

230 192 172 ? 122 100

9       14       38       129       ?      2705      16260

What will come in place of (?) in the following number series problems? 

6,  ?, 36, 180,  1260,  13860

580 557 528 497 ? 419

? , 864, 432, 144, 36, 7.2

  5, 6, 14, 45, 184,  ?   

9000, 1800, 450, ?, 75, 75