
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
A shopping mall wants to quickly estimate the monthly total sales by checking 2% of the invoices and sales records. Now, using systematic sampling, they randomly select one out of 50 invoice stubs, such as number 15, and then continue to draw in sequence, such as 15, 65, 115…, what is the number of the fifth invoice?

Present the answer in LaTex format: \boxed{Your answer}
user