Find the next number in the series:
$16,10,20,14,24,\_\_\_\_\_$

The system consists of two alternating tracks:
* Track 1 (Odd items): $16\stackrel{+4}{\to }20\stackrel{+4}{\to }24$
* Track 2 (Even items): $10\stackrel{+4}{\to }14\stackrel{+4}{\to }?$

The blank falls on the 6th element, which is part of the second track:

$$\text{Next value}=14+4=18$$