Calculate (-1)^99: Evaluating Powers of Negative One

To solve this problem, we'll follow these steps:

• Step 1: Determine the nature of the exponent (odd or even).
• Step 2: Apply the specific rule for the power of $-1$ based on the exponent's nature.

Now, let's work through each step:
Step 1: The exponent is $99$, which is odd.
Step 2: For the power of $-1$, the rule states that if the exponent is odd, $(-1)^n = -1$. Thus, $(-1)^{99} = -1$.

Therefore, the solution to the problem is $-1$.