There are 18 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18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">18 * 4</gadget>
<output>72</output>

<gadget id="calculator">72 - 18</gadget>
<output>54</output>

<result>54</result>