Answer:
Sum: 315.6974
Rounded to the nearest hundredth: 315.70
Rounded to the nearest thousandth: 315.697
Explanation:
First, add 84.0393 and 231.6581 to get a sum of 315.6974.
To round to the nearest hundredth, is the number next to it bigger than 5?
In this case, yes. So you go up.
Basically the same procedure with the thousandths.
Does the number accompanying it go larger than 5?
No.