Step-by-step Solution:

Quick Solution

This number series puzzle can be solved by looking for a pattern in the difference between the consecutive terms. This is a common type of second-order series.

1. Find the Difference Between Terms

Let's write down the series and calculate the difference between each pair of numbers:

120    99    80    63    48    ...
    ╰─ -21 ─╯  ╰─ -19 ─╯  ╰─ -17 ─╯  ╰─ -15 ─╯  ╰─ ? ─╯

2. Identify the Pattern in the Differences

- The series formed by the differences is: 21, 19, 17, 15, ... - We can see a clear and simple pattern here: it's a sequence of decreasing odd numbers, where 2 is subtracted each time to get the next term.
- The next difference in this pattern should therefore be 15 - 2 = 13.

3. Find the Next Number in the Original Series

- To find the next number in the original series, we subtract this next difference (13) from the last known term (48):

48 - 13 = 35

Final Answer: The number that comes next in the series is 35.