The sum of 2.25 and 3.50 is:

$2.25 + 3.50 = 5.75$

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

1. What is 2.25 plus 3.75?
2. How do you convert a decimal into a fraction?
3. How do you round 5.75 to the nearest whole number?
4. What is the difference between addition and subtraction of decimals?
5. How can you solve problems with multiple decimal numbers?

Tip: Always align the decimal points vertically when adding or subtracting decimals to ensure accurate calculations.