A rectangular open space is 30 meters long and 45 meters wide. If one poplar is planted every 3 square meters, how many trees can there be in total?
一个长方形空地，长是30米，宽是45米，如果每3平方米种一棵杨树，一共可以各多少棵？
<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">45 * 10</gadget>
<output>450</output>

<result>450</result>