To round 6.4 to the nearest whole number, follow these steps:
Identify the decimal part: In the number 6.4, the first digit after the decimal point is 4.
Apply rounding rules: Since the first digit after the decimal point (4) is less than 5, you keep the number unchanged.
Final rounded result: The number remains the same 6.
Thus, 6.4 rounded to the nearest whole number is 6.