Cut out the largest square from a rectangular paper with a length of 20 decimeters and a width of 15 decimeters, what is the remaining area in square centimeters?
在一个长20分米，宽15分米的长方形纸上剪去一个最大的正方形，剩下的面积是多少平方厘米？
<gadget id="calculator">20 * 15</gadget>
<output>300</output>

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

<gadget id="calculator">300 - 225</gadget>
<output>75</output>

<gadget id="calculator">75 * 100</gadget>
<output>7_500</output>

<result>7_500</result>