1. **State the problem:** Find the circumference of a circle given the diameter is 12 inches. 2. **Formula:** The circumference $C$ of a circle is given by the formula: $$C = \pi d$$ where $d$ is the diameter. 3. **Substitute the given diameter:** $$C = \pi \times 12$$ 4. **Calculate the circumference:** $$C = 12\pi$$ 5. **Interpretation:** The circumference is $12\pi$ inches, which is approximately $12 \times 3.1416 = 37.6992$ inches. **Final answer:** $$\boxed{12\pi \text{ inches} \approx 37.7 \text{ inches}}$$