Answer:
6
Explanation:
To round 6.4 to the nearest whole number, you first must see if the number given is above or below the .5 mark.
6.4 is below it, so you would be rounding down.
Because you are rounding the the NEAREST whole number, you know that 6 is closer than 7, which gives you your answer.
Also, because you know you are rounding DOWN to the nearest whole number, you know it is 6.