Which value among $\sqrt[3]{8}, \sqrt[2]{4}, \sqrt[6]{64}$ is greatest?

$\sqrt[3]{8}=\left(2^{3}\right)^{\frac{1}{3}}=2$

$\sqrt[2]{4}=\left(2^{2}\right)^{\frac{1}{2}}=2$

$\sqrt[6]{64}=\left(2^{6}\right)^{\frac{1}{6}}=2$

$\therefore \sqrt[3]{8}=\sqrt[2]{4}=\sqrt[6]{64}$