$8^{3 \log _{8} 5}$ is equal to

Using the logarithmic property $a^{\log_{a} b} = b$, we rewrite the expression $8^{3 \log_{8} 5}$.

Applying the power rule for logarithms, $n \log_{a} b = \log_{a} (b^n)$, we get:

$3 \log_{8} 5 = \log_{8} (5^3)$

Substituting this back into the expression:

$8^{\log_{8} (5^3)} = 5^3$

Calculating the value:

$5^3 = 125$

Answer: 125