1. **State the problem:** Calculate the sum of 1 + 1. 2. **Formula used:** Addition of two numbers is given by $a + b$ where $a$ and $b$ are numbers. 3. **Apply the formula:** Here, $a = 1$ and $b = 1$, so $$1 + 1 = 2$$ 4. **Explanation:** Adding one and one means combining two single units, which results in two units. 5. **Final answer:** The sum of 1 + 1 is 2.