To simplify the expression \((78^8)^6\) using the power of a power property of exponents, you can multiply the exponents. The property states that \((a^m)^n = a^{m \cdot n}\).
Applying this to your expression:
\[ (78^8)^6 = 78^{8 \cdot 6} = 78^{48} \]
So, the simplified expression is:
\[ 78^{48} \]