Simplify $\dfrac{(0.5)^{-3} \cdot (0.25)^{2}}{(0.125)^{-1}}$.

Simplify $\dfrac{(0.5)^{-3} \cdot (0.25)^{2}}{(0.125)^{-1}}$.
  1. $\dfrac{1}{16}$
  2. $16$
  3. $\dfrac{1}{8}$
  4. $\dfrac{1}{2}$

Solution

Write each as a power of 2: $0.5 = 2^{-1}$, $0.25 = 2^{-2}$, $0.125 = 2^{-3}$. Then $(2^{-1})^{-3} \cdot (2^{-2})^{2} \div (2^{-3})^{-1} = 2^{3} \cdot 2^{-4} \div 2^{3} = 2^{-4} = \dfrac{1}{16}$.

Asked in: IMO

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