The stationery store shipped 5 boxes of pens, each with 4 boxes of 20 pens. How many of these pens are there?
文具店运来5箱钢笔，每箱有4盒，每盒有20支．这些钢笔一共有多少支？
<gadget id="calculator">5 * 4 * 20</gadget>
<output>400</output>

<result>400</result>