
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
Xiao Wang saves about $a$ yuan each month after all daily expenses. Xiao Wang decides to adopt a lump-sum deposit method to save the remaining money, depositing $a$ yuan at the beginning of each month into the bank. The deposit period is 1 year (deposited 12 times), and the principal and interest are withdrawn upon maturity. Assuming the monthly interest rate for the lump-sum deposit for one year is $r$, and the interest on each deposit is calculated using simple interest. Then, the interest Xiao Wang earns upon maturity is __________ yuan.

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