1. **State the problem:** Calculate the sum of 3 and 8. 2. **Formula used:** Addition of two numbers is given by $a + b$ where $a$ and $b$ are numbers. 3. **Apply the formula:** Here, $a = 3$ and $b = 8$, so we calculate $3 + 8$. 4. **Perform the addition:** $3 + 8 = 11$. 5. **Conclusion:** The sum of 3 and 8 is 11.