1. **State the problem:** We need to find the mass of gold given its density and volume. 2. **Formula:** Mass is calculated by the formula $$\text{Mass} = \text{Density} \times \text{Volume}$$ 3. **Important rules:** - Density must be in consistent units with volume. - Volume is given in mm³, but density is in g/cm³, so convert volume to cm³. 4. **Convert volume:** Since $$1\ \text{cm}^3 = 1000\ \text{mm}^3$$, $$40\ \text{mm}^3 = \frac{40}{1000} = 0.04\ \text{cm}^3$$ 5. **Calculate mass:** $$\text{Mass} = 19.3\ \frac{g}{cm^3} \times 0.04\ cm^3$$ $$= 0.772\ g$$ 6. **Final answer:** The mass of 40 mm³ of gold is **0.772 grams**.