1. The problem is to add a whole number and a fraction: $3 + \frac{1}{3}$. 2. To add these, express the whole number as a fraction with the same denominator as the fraction part. Since the fraction has denominator 3, write $3$ as $\frac{3 \times 3}{3} = \frac{9}{3}$. 3. Now add the fractions: $$\frac{9}{3} + \frac{1}{3} = \frac{9 + 1}{3} = \frac{10}{3}.$$ 4. The result is an improper fraction $\frac{10}{3}$, which can also be written as the mixed number $3 \frac{1}{3}$. Final answer: $3 + \frac{1}{3} = \frac{10}{3} = 3 \frac{1}{3}$.