Q.Evaluate:

A fractional exponent of the form $1/n$ represents the $n$-th root.

(i) $16^{1/2}$

A power of $1/2$ is the square root: $16^{1/2}=\sqrt{16}=4$, since $4\times4=16$.

(ii) $27^{1/3}$

A power of $1/3$ is the cube root: $27^{1/3}=\sqrt[3]{27}=3$, since $3\times3\times3=27$. …

Confusing the denominator of the fractional exponent with a division of the base (e.g. wrongly computing $16^{1/2}$ as $16\div2=8$) instead of recognising it as a root; also mixing up which root the …