Xiaohong has 3 tops and 4 pairs of trousers, which make up a set of clothes. How many different collocations are there?
小红有3件上衣和4条裤子，配成一套衣服，有多少种不同的搭配．
<gadget id="calculator">3 * 4</gadget>
<output>12</output>

<result>12</result>