The school is going to distribute exercise books to 20 classes, each class has 120 copies, and 60 copies need to be kept for spare. How many exercise books should schools buy?
学校准备发练习本，发给20个班，每班120本，还需要留60本备用．学校应买多少本练习本？
<gadget id="calculator">120 * 20</gadget>
<output>2_400</output>

<gadget id="calculator">2_400 + 60</gadget>
<output>2_460</output>

<result>2_460</result>