The sum of $123456 + 700000$ is:

$123456 + 700000 = 823456$

Would you like further clarification or have any questions?

Here are some related questions:

1. What is $823456 \times 2$?
2. How do you subtract large numbers efficiently?
3. What is the sum of $123456 + 789012$?
4. How do you round large numbers to the nearest ten thousand?
5. What is $700000 - 123456$?

Tip: When adding large numbers, it's often helpful to break them down into smaller parts (e.g., adding in parts like 100000, 200000, etc.) for easier mental calculations.