Find the missing number in the series.
$$20,35,60,105,190,\_\_\_\_$$

Let's find the difference between consecutive terms:
* $35-20=15$
* $60-35=25$
* $105-60=45$
* $190-105=85$

Now, observe the pattern in the differences ($15,25,45,85$):

* $25-15=10$
* $45-25=20$
* $85-45=40$

The differences between the differences are doubling each time ($10,20,40$).
So, the next difference of difference should be $40\times 2=80$.
The next difference to add to the series term will be $85+80=165$.

$$\text{Missing number}=190+165=355$$

Alternative Method:
Each term is generated by multiplying the previous term by $2$ and subtracting an increasing multiple of $5$:

* $20\times 2-5=35$
* $35\times 2-10=60$
* $60\times 2-15=105$
* $105\times 2-20=190$
* $190\times 2-25=380-25=355$