The library has bought 4 new books, and Xiaoli wants to borrow 2 of them. How many different borrowing methods are there?
图书馆新买了4本新书，小丽想借其中的2本，一共有多少种不同的借法．
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">4 * (3/2)</gadget>
<output>6</output>

<result>6</result>