
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
Person A writes down a four-digit number \( A \) on the blackboard. Person B adds a digit to the front and another digit to the back of this four-digit number to create a six-digit number \( B \). If \( B \) divided by \( A \) gives a quotient of 21 and a remainder of 0, find the values of \( A \) and \( B \).

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