Take a square of cardboard with a side length of 10 cm and cut out a rectangle with a length of 10 cm and a width of 6 cm. What is the shape of the remaining part? What is its area in square centimeters?
拿一张边长是10厘米的正方形纸板，剪下一个长10厘米，宽6厘米的长方形，剩下的部分是什么形？它的面积是多少平方厘米？
<gadget id="calculator">10 * 4</gadget>
<output>40</output>

<result>40</result>