Multiply Powers: Solving (-1)^99 × (-1)^9

To solve this problem, we need to evaluate the expression $(-1)^{99} \cdot (-1)^9$.

The first step is to evaluate each component:

• Step 1: Evaluate $(-1)^{99}$.
  Since 99 is an odd number, $(-1)^{99} = -1$. This is because any odd power of $-1$ results in $-1$.
• Step 2: Evaluate $(-1)^9$.
  Similarly, since 9 is also an odd number, $(-1)^9 = -1$. Again, an odd exponent means the result is $-1$.

Step 3: Multiply the results from step 1 and step 2:
$(-1)^{99} \cdot (-1)^9 = (-1) \cdot (-1) = 1$.

Thus, the value of the expression is $\boxed{1}$.