A piece of square paper with a side length of 40 cm, cut off a small square piece of paper with a side length of 10 cm from each of its four corners, what is the area of the remaining part in cm**2.
一张边长为40cm的正方形纸，在它的四个角上，各剪去一个边长为10cm的小正方形纸片，剩下部分的面积是多少cm**2．
<gadget id="calculator">40 * 40</gadget>
<output>1_600</output>

<gadget id="calculator">10 * 10 * 4</gadget>
<output>400</output>

<gadget id="calculator">1_600 - 400</gadget>
<output>1_200</output>

<result>1_200</result>