### Instruction: What is the tens digit of $5^{2005}$?### Response: I need to find the last two digits of $5^{2005}$, since the tens digit is the second-to-last digit.
I notice that powers of 5 have a repeating pattern for their last two digits: 25, 25, 25, ..., no matter how high the exponent is.
So I can conclude that the last two digits of $5^{2005}$ are also 25.
Therefore, the tens digit is 2.