1. **State the problem:** We need to find how many dominoes, each 0.6 cm thick, are required to make a stack 8.4 cm high. 2. **Formula used:** To find the number of dominoes, use the formula: $$\text{Number of dominoes} = \frac{\text{Total height}}{\text{Thickness of one domino}}$$ 3. **Apply the values:** $$\text{Number of dominoes} = \frac{8.4}{0.6}$$ 4. **Calculate:** $$\frac{8.4}{0.6} = 14$$ 5. **Interpretation:** It would take 14 dominoes stacked on top of each other to reach a height of 8.4 cm. **Final answer:** 14 dominoes.