What will come in place of the question mark in the following series?
$$12,18,36,90,270,?$$

Analyze the constant factor multiplying successive terms in the sequence:
* $12\times 1.5=18$
* $18\times 2.0=36$
* $36\times 2.5=90$
* $90\times 3.0=270$

The multiplication factor is incrementing by $0.5$ at each subsequent step. Following this trend, the next multiplier must be $3.5$:

$$\text{Missing Term}=270\times 3.5=945$$