Qianjin Primary School purchased a total of 900 books for each class. The school has 6 grades, and each grade has 5 classes. How many books does each class have on average?
前进小学为每班共购买了900本书，学校有6个年级，每个年级有5个班，平均每班有多少本书？
<gadget id="calculator">5 * 6</gadget>
<output>30</output>

<gadget id="calculator">900 / 30</gadget>
<output>30</output>

<result>30</result>