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

Would you like more details or have any questions?

Here are some related questions to consider:

1. What is $2 + 3$?
2. How do you add two numbers together?
3. What is the sum of $5 + 7$?
4. How does addition differ from multiplication?
5. Can we represent addition visually on a number line?

Tip: To add two numbers, start from the first number and count forward by the second number.