The school library has newly bought 5 different best-selling books. Xiaoli wants to borrow 2 of them. How many different borrowing methods are there?
学校图书馆新买来5本不同的畅销书，小丽想借其中的2本，一共有多少种不同的借法．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<result>10</result>