What is the area of the remaining part after cutting out the largest square from a rectangular cardboard with a length of 8 cm and a width of 5 cm?
从一个长8cm，宽5cm的长方形纸板中剪出一个最大的正方形后，余下部分的面积是多少．
<gadget id="calculator">8 - 5</gadget>
<output>3</output>

<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<result>15</result>