The school is going to distribute exercise books to 18 classes, each class has 156 copies, and 120 copies need to be prepared as spares. How many exercise books should schools buy?
学校准备发练习本，发给18个班，每班156本，还需要准备120本作为备用．学校应买多少本练习本？
<gadget id="calculator">156 * 18</gadget>
<output>2_808</output>

<gadget id="calculator">2_808 + 120</gadget>
<output>2_928</output>

<result>2_928</result>