1. **State the problem:** We need to find the missing height $h$ of a rectangular prism given its volume and base dimensions. 2. **Formula:** The volume $V$ of a rectangular prism is given by $$V = \text{length} \times \text{width} \times \text{height}$$ 3. **Given values:** - Volume $V = 1620$ cm$^3$ - Length $= 9$ cm - Width $= 9$ cm - Height $= h$ cm (unknown) 4. **Set up the equation:** $$1620 = 9 \times 9 \times h$$ 5. **Simplify the multiplication:** $$1620 = 81 \times h$$ 6. **Solve for $h$ by dividing both sides by 81:** $$h = \frac{1620}{81}$$ 7. **Show cancellation:** $$h = \frac{\cancel{1620}}{\cancel{81}} = 20$$ 8. **Final answer:** $$h = 20 \text{ cm}$$ The missing height of the prism is 20 cm.