Indices, Standard Form & Surds

Laws of indices

$$a^m \times a^n = a^{m+n}, \quad \frac{a^m}{a^n} = a^{m-n}, \quad (a^m)^n = a^{mn}$$ $$a^0 = 1, \quad a^{-n} = \frac{1}{a^n}, \quad a^{\frac{1}{n}} = \sqrt[n]{a}, \quad a^{\frac{m}{n}} = \left(\sqrt[n]{a}\right)^m$$

So $16^{\frac{3}{4}} = (\sqrt[4]{16})^3 = 2^3 = 8$