The problem is asking to "Add 9" starting from the given number, 108. Here's the solution:

1. Start with 108.
2. Add 9 to get the next number: $108 + 9 = 117$.
3. Add 9 again: $117 + 9 = 126$.
4. Add 9 again: $126 + 9 = 135$.
5. Add 9 again: $135 + 9 = 144$.

The sequence is: 108, 117, 126, 135, 144.

Would you like a detailed explanation of any of the steps? Here are some related questions to expand your understanding:

1. How do you identify an arithmetic sequence?
2. What is the formula for the $n$-th term of an arithmetic sequence?
3. How do you find the sum of an arithmetic sequence?
4. Can arithmetic sequences model real-life scenarios?
5. What happens if you subtract 9 instead of adding 9 in a sequence?

Tip: In arithmetic sequences, the difference between consecutive terms remains constant, making them predictable and easy to extend.