Uncle Wang planted cabbage in a square field with a side length of 15 meters, and planted 4 cabbages per square meter. How many cabbages will be planted in this field?
王大伯在一块边长15米的正方形地里种白菜，每平方米种4棵．这块地里一共要种白菜多少棵？
<gadget id="calculator">15 * 15 * 4</gadget>
<output>900</output>

<result>900</result>