The sum of $2 + 4$ is $6$.

Would you like details on how addition works or have any other questions?

Here are 5 related questions:

1. What is $3 + 5$?
2. How do you add two-digit numbers?
3. What is the sum of $10 + 15$?
4. How does addition differ from subtraction?
5. How can you add numbers mentally more quickly?

Tip: When adding, it's often helpful to group numbers that sum to 10 first, as this makes calculations quicker.