There are 25 boxes of table tennis balls in a box, and each box has 5 balls. How many such ping-pong balls are there in 4 boxes?
一箱乒乓球有25盒，每盒5个．4箱这样的乒乓球一共有多少个？
<gadget id="calculator">5 * 25 * 4</gadget>
<output>500</output>

<result>500</result>