There are 45 students in each class of the third and fourth grades, and each grade has 5 classes. How many students are there in the two grades?
三、四年级每班有45人，每个年级都有5个班，两个年级共有多少人？
<gadget id="calculator">5 * 2 * 45</gadget>
<output>450</output>

<result>450</result>