There are 7 poplar trees in the park, and the number of willow trees is 9 times that of poplar trees. How many willow trees are there?
公园有杨树7棵，柳树的棵数是杨树的9倍，柳树有多少棵？
<gadget id="calculator">7 * 9</gadget>
<output>63</output>

<result>63</result>