1. **State the problem:** Multiply 6 by 12. 2. **Formula used:** Multiplication of two numbers $a$ and $b$ is given by $a \times b$. 3. **Apply the formula:** Here, $a=6$ and $b=12$, so calculate $6 \times 12$. 4. **Intermediate work:** $6 \times 12 = 72$. 5. **Explanation:** Multiplying 6 by 12 means adding 6 twelve times or 12 six times, which results in 72. **Final answer:** $72$