The result of $1 + 2$ is $3$.

Would you like further details on addition, or do you have any more questions?

Here are some related questions:

1. What is the associative property of addition?
2. How do you perform addition with larger numbers?
3. What is the difference between addition and subtraction?
4. How do you add negative numbers?
5. What is the identity element for addition?

Tip: The identity element for addition is $0$, because adding $0$ to any number leaves it unchanged.