To simplify the expression \( 5^{10} \cdot 5^{-6} \), we can apply the property of exponents that states:
\[ a^m \cdot a^n = a^{m+n} \]
In this case, we have:
\[ 5^{10} \cdot 5^{-6} = 5^{10 + (-6)} = 5^{10 - 6} = 5^4 \]
Now, we need to find the numerical value of \( 5^4 \).
Calculating \( 5^4 \):
\[ 5^4 = 5 \times 5 \times 5 \times 5 \]
Calculating step by step:
- \( 5 \times 5 = 25 \)
- \( 25 \times 5 = 125 \)
- \( 125 \times 5 = 625 \)
Thus, \( 5^4 = 625 \).
So, the numerical equivalent of \( 5^{10} \cdot 5^{-6} \) is
\[ \boxed{625} \]