Xiaohong has 2 coats of different colors and 2 pairs of pants of different colors. How many matching methods are there in total?
小红有2件不同颜色的上衣，有2条不同颜色的裤子，共有多少种搭配方法．
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<result>4</result>