
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
Murtha extends her pebble collection habit. She collects one pebble on the first day and increases her collection by one additional pebble each subsequent day. How many pebbles will she have collected at the end of the fifteenth day?

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