1. The problem is to round the number 3.11 to the nearest whole number. 2. The rule for rounding to the nearest whole number is: if the decimal part is 0.5 or greater, round up; if it is less than 0.5, round down. 3. Here, the decimal part of 3.11 is 0.11, which is less than 0.5. 4. Therefore, we round down 3.11 to 3. 5. The final answer is 3.