The sum of 55 and 34 is:

$55 + 34 = 89$

Would you like further details or any questions? Here are some related questions for you:

1. What is 55 - 34?
2. What is 55 × 34?
3. How do you add two numbers using the distributive property?
4. What is 55 + 34 in binary form?
5. Can you explain why addition is commutative (i.e., $a + b = b + a$)?

Tip: When adding numbers, it can be helpful to break them into tens and ones for easier mental calculations.