1. **State the problem:** Convert $54x^{-8} \text{ m}^3$ to $\text{mm}^3$. 2. **Recall the conversion factor:** Since $1 \text{ m} = 1000 \text{ mm}$, then $$1 \text{ m}^3 = (1000 \text{ mm})^3 = 1000^3 \text{ mm}^3 = 10^9 \text{ mm}^3$$ 3. **Apply the conversion:** $$54x^{-8} \text{ m}^3 = 54x^{-8} \times 10^9 \text{ mm}^3$$ 4. **Simplify the expression:** $$54 \times 10^9 x^{-8} \text{ mm}^3 = 5.4 \times 10^{10} x^{-8} \text{ mm}^3$$ 5. **Final answer:** $$\boxed{5.4 \times 10^{10} x^{-8} \text{ mm}^3}$$