Answer
To round a mixed number to the nearest whole number, look at the fraction. If it is greater than $\frac{1}{2}$ then round up to the nearest whole number, if it is smaller than $\frac{1}{2}$ then round down to the nearest whole number.
Work Step by Step
For example, to round $3\frac{7}{9}$ to the nearest whole number, look at the fraction. $\frac{7}{9} \gt \frac{1}{2}$ so round up to 4.