There are 5 classes in the fourth grade, and each class orders 4 packs of math exercise books, each pack of 120 books. How many math exercise books were ordered in the fourth grade?
四年级共有5个班，每个班订数学练习本4包，每包120本．四年级共订了多少本数学练习本？
<gadget id="calculator">4 * 5 * 120</gadget>
<output>2_400</output>

<result>2_400</result>