After cutting the largest square out of a rectangular piece of paper 9 cm long and 6 cm wide, what figure is left? What is the remaining area in square centimeters?
在一张长9厘米，宽6厘米的长方形纸上剪去一个最大的正方形后，剩下的是什么图形？剩下的面积是多少平方厘米？
<gadget id="calculator">9 - 6</gadget>
<output>3</output>

<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<result>18</result>