Identify a pattern in the given list of numbers. Then use this pattern to find the next number. (More than one pattern might exist, so it is possible that there is more than one correct answer.)
\[
9,21,33,45,57 \text {, }
\]
The next number is

Step 1 ：Identify a pattern in the given list of numbers. Then use this pattern to find the next number. More than one pattern might exist, so it is possible that there is more than one correct answer.

Step 2 ：The given sequence is \(9, 21, 33, 45, 57\).

Step 3 ：The sequence is an arithmetic sequence. In an arithmetic sequence, the difference between any two successive members is a constant. Let's find the common difference of the sequence.

Step 4 ：The common difference of the sequence is \(12\). This means that each number in the sequence is \(12\) more than the previous number.

Step 5 ：To find the next number in the sequence, we can add \(12\) to the last number in the sequence.

Step 6 ：The next number in the sequence is \(69\).

Step 7 ：Final Answer: The next number in the sequence is \(\boxed{69}\).