Identify the incorrect number in the following series:
$$12,10,6,1,-8,-18$$

Let's analyze the differences between consecutive terms in the series:
* $10-12=-2$
* $6-10=-4$

If the pattern of differences continues as consecutive decreasing even numbers ($-2,-4,-6,-8,-10$), the subsequent terms ought to be:

* $\text{Fourth term}=6-6=0$ (instead of $1$)
* $\text{Fifth term}=0-8=-8$
* $\text{Sixth term}=-8-10=-18$

Since replacing the number $1$ with $0$ makes the entire sequence perfectly consistent, the incorrect number in the series is $1$.