There are 4 grades in Xicheng Primary School participating in the tree planting activity, each grade has 3 classes, and an average of 35 trees are planted in each class, how many trees are planted in total?
西城小学有4个年级参加植树活动，每个年级有3个班，平均每班植树35棵，一共植树多少棵？
<gadget id="calculator">35 * 3 * 4</gadget>
<output>420</output>

<result>420</result>