The school bought 5 identical reference books for the teacher. Each book is 8mm thick, how many millimeters are there in total?
学校为老师买来5本同样的参考书．每本厚8毫米，一共厚多少毫米？
<gadget id="calculator">8 * 5</gadget>
<output>40</output>

<result>40</result>