The school bought 53 story books and distributed them to 8 classes. If there are 7 copies for each class, how many more copies should I buy?
学校买来53本故事书，分给8个班．如果每班要分到7本，还要再买几本？
<gadget id="calculator">7 * 8</gadget>
<output>56</output>

<gadget id="calculator">56 - 53</gadget>
<output>3</output>

<result>3</result>