Which of the following numbers will replace the question mark (?) in the given series?
165,192,227,270,321,?

Let's calculate the differences between consecutive numbers in the series:
192−165=27

227−192=35

270−227=43

321−270=51

Now, let's analyze the sequence of these first-level differences (27,35,43,51):

35−27=8

43−35=8

51−43=8

The first-level differences increase by a constant value of +8 (double difference series).

Following this rule, the next first-level difference will be:

51+8=59
Thus, the missing number in the series is:

Missing number=321+59=380