Three classmates went to the library to borrow science fiction novels, and found that there were only 9 books left on the shelf, and they were all different. If each person borrows only one book, how many different ways of borrowing are there?
3名同学一块去图书馆借科幻小说，发现书架上只剩下9本，且各不相同．如果每人只借1本，那么共有多少种不同的借法？
<gadget id="calculator">9 * 8 * 7</gadget>
<output>504</output>

<gadget id="calculator">3 * 2 * 1</gadget>
<output>6</output>

<gadget id="calculator">504 / 6</gadget>
<output>84</output>

<result>84</result>