There are 180 pine saplings, and the number of poplar saplings is 4 times that of pine saplings. How many more poplar saplings are there than pine saplings?
松树苗有180棵，杨树苗的棵树是松树苗的4倍，杨树苗比松树苗多多少棵？
<gadget id="calculator">180 * 4</gadget>
<output>720</output>

<gadget id="calculator">720 - 180</gadget>
<output>540</output>

<result>540</result>