To round 166.66 to the nearest whole number, follow these steps:
Identify the decimal part: In the number 166.66, the first digit after the decimal point is 6.
Apply rounding rules: Since the first digit after the decimal point (6) is greater than or equal to 5, you round the number up by 1.
Final rounded result: The number becomes 167.
Thus, 166.66 rounded to the nearest whole number is 167.