1. **State the problem:** We have a rectangular box with a height of 15 cm and the area of its base is 210 cm². We need to find the volume of the box. 2. **Formula used:** The volume $V$ of a rectangular box is given by the formula: $$V = \text{base area} \times \text{height}$$ 3. **Apply the values:** Substitute the given base area and height into the formula: $$V = 210 \times 15$$ 4. **Calculate the volume:** $$V = 3150$$ 5. **Interpretation:** The volume of the box is 3150 cubic centimeters. This means the box can hold 3150 cubic centimeters of space inside it.