
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 number in the form of $7777 \cdots 77$ is written on the blackboard. Each time the last digit is erased, the remaining number is multiplied by 3, and then the erased digit is added back. This operation is continued repeatedly. What is the final number obtained?

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