There are 40 students in Class 1 to borrow books from the library. It is necessary to ensure that at least one student can borrow 3 books. How many books should the library have at least?
六1班有40名学生到图书室借书，要保证至少有一名学生能借到3本书，这个图书室至少要有多少本书？
<gadget id="calculator">40 * 2</gadget>
<output>80</output>

<gadget id="calculator">80 + 1</gadget>
<output>81</output>

<result>81</result>