A cuboid swimming pool needs to be tiled, the length and width are 4m, and the height is 5m. At least how many m**2 tiles are needed to lay such a swimming pool?
一个长方体的游泳池要铺瓷砖，长和宽都是4m，高是5m．铺这样的游泳池至少需要瓷砖多少m**2？
<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<gadget id="calculator">4 * 5 * 2</gadget>
<output>40</output>

<gadget id="calculator">20 + 40 + 40</gadget>
<output>100</output>

<result>100</result>