There is a rectangular vegetable field in Zhangcun with an area of 21 square meters. A square with a side length of 4 meters is marked out to plant pollution-free Chinese cabbage. What percentage of the area does the pollution-free Chinese cabbage occupy?
张村有一块长方形菜地面积为21平方米，划出一块边长为4米的正方形地种无公害大白菜，种无公害大白菜的面积占这块地的几分之几？
<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<gadget id="calculator">16 / 21</gadget>
<output>16/21 = around 0.761905</output>

<result>16/21 = around 0.761905</result>