
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
(2012•Hubei) A palindrome is a positive integer that reads the same backward as forward, such as 22, 11, 3443, 94249, etc. Clearly, there are 9 two-digit palindromes: 11, 22, 33…, 99. There are 90 three-digit palindromes: 101, 111, 121, …, 191, 202, …, 999. Then: (I) There are ___ four-digit palindromes;  
(II) There are ___ palindromes with $2n+1$ ($n\in\mathbb{N}^+$) digits.

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