To solve for \( 9^9 \cdot 9^{-6} \), we can use the properties of exponents. In particular, we can use the rule that states \( a^m \cdot a^n = a^{m+n} \).
Here, we have:
\[ 9^9 \cdot 9^{-6} = 9^{9 + (-6)} = 9^{9 - 6} = 9^3 \]
Now, we need to compute \( 9^3 \):
\[ 9^3 = 9 \cdot 9 \cdot 9 \]
Calculating this step-by-step:
- Calculate \( 9 \cdot 9 = 81 \)
- Then, calculate \( 81 \cdot 9 \):
\[ 81 \cdot 9 = 729 \]
Thus, the numerical equivalent of \( 9^9 \cdot 9^{-6} \) is:
\[ \boxed{729} \]