Given:
15.870 + 6.77
We are required to round each number to the nearest tenth before performing the addition.
The tenth digit is the number first number after the decimal point.
First step:
Round to the nearest tenth
15.870 ==> 15.9
6.77 ==> 6.8
Second step:
Add both numbers after rounding to the nearest tenth
15.9 + 6.8 = 22.7
ANSWER:
22.7