
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
On the board, a natural number is written. If its last digit (units place) is erased, the remaining non-zero number is divisible by 20. If its first digit is erased, the number is divisible by 21. What is the smallest number that can be written on the board if its second digit is not zero?

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