Well since it's better to teach you than answer, I'll give you an explanation using #1.
Answer:
6.88
Explanation:
In the parentheses, 1.6 has one decimal place, and so does 4.3. (count number of digits after decimal point.) So a total of 2 decimal places. (1) + (1) = (2)
Next, ignore the decimal points for now and multiply 16 × 43 = 688.
Add in the 2 decimal places, 6.88, there is your answer!