$\left(\dfrac{2}{3}\right)^5 \times \left(\dfrac{2}{3}\right)^{-5} = ?$ (Example 1)

Adding exponents for like bases gives $\left(\tfrac{2}{3}\right)^{5+(-5)}=\left(\tfrac{2}{3}\right)^0=1$. Any nonzero base raised to the zero power equals .