To calculate 4% of 80, you can use the following formula:
\[ \text{Percentage} = \left(\frac{\text{percent}}{100}\right) \times \text{whole} \]
So:
\[ 4% \text{ of } 80 = \left(\frac{4}{100}\right) \times 80 = 0.04 \times 80 = 3.2 \]
Therefore, the answer is 3.2.