
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
Xiaoming's home phone number was originally a six-digit number. The first upgrade involved adding the digit 8 between the first and second digits, turning it into a seven-digit phone number; the second upgrade involved adding the digit 2 in front of the first digit, turning it into an eight-digit phone number. Xiaoming found that the eight-digit phone number after two upgrades was exactly 81 times the original six-digit phone number. What was Xiaoming's original phone number?

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