1. **State the problem:** We need to find the volume of a cylindrical tin of paint with radius $r=9$ cm and height $h=20$ cm. 2. **Formula for the volume of a cylinder:** The volume $V$ of a cylinder is given by the formula: $$V = \pi r^2 h$$ where $r$ is the radius and $h$ is the height. 3. **Substitute the given values:** $$V = \pi \times 9^2 \times 20$$ 4. **Calculate the square of the radius:** $$9^2 = 81$$ 5. **Multiply the values:** $$V = \pi \times 81 \times 20$$ 6. **Simplify the multiplication:** $$V = 1620 \pi$$ **Final answer:** The volume of the cylindrical tin is $$1620 \pi \text{ cubic centimeters}$$