piece of rectangular paper with a length of 28 cm and a width of 15 cm, cut out the largest square, what is the area of the remaining part?
一张长方形的纸，长是28厘米，宽是15厘米，剪下一个最大的正方形，剩余部分的面积是多少？
<gadget id="calculator">28 * 15</gadget>
<output>420</output>

<gadget id="calculator">15 * 15</gadget>
<output>225</output>

<gadget id="calculator">420 - 225</gadget>
<output>195</output>

<result>195</result>