There are 42 people in class 4, and 6 trees are planted per person on average; there are 45 people in class 2, 5 trees are planted per person on average. How many trees did the two classes plant in total?
四1班有42人，平均每人栽了6棵树；四2班有45人，平均每人栽5棵树．两个班一共植树多少棵？
<gadget id="calculator">42 * 6</gadget>
<output>252</output>

<gadget id="calculator">45 * 5</gadget>
<output>225</output>

<gadget id="calculator">252 + 225</gadget>
<output>477</output>

<result>477</result>