Step-by-step explanation:
2.334 = 4 SF and 3 SF to the right to the decimal point.
0.31 = 2 SF and 2 SF to the right to the decimal point.
2.334 + 0.31 = 2.664
The rule says: "For addition and subtraction problems, the answer should be rounded to the same number of decimal places as the measurement with the least number of decimal places".
The measurement or number with the least number of decimal places is 0.31 that has 2 decimal places. The we should round it there.
2.334 + 0.31 = 2.664 = 2.66
Answer: 2.66