The sum of $1.64 + 0.728$ is:

$1.64 + 0.728 = 2.368$

So, the result is $2.368$.

Would you like more details or have any questions?

Here are 5 related questions:

1. What is $1.64 - 0.728$?
2. How do you round $2.368$ to two decimal places?
3. What is $1.64 \times 0.728$?
4. How do you express $2.368$ as a fraction?
5. What is $2.368$ divided by 2?

Tip: When adding decimals, align the numbers by their decimal points for an accurate result.