The school playground was originally 100 meters long and 60 meters wide. After the expansion, the length and width increased by 20 meters respectively. How many square meters has the playground area increased after the expansion?
学校操场原来长100米，宽60米，扩建后长与宽分别增加20米，扩建后这个操场面积增加了多少平方米？
<gadget id="calculator">100 + 20</gadget>
<output>120</output>

<gadget id="calculator">60 + 20</gadget>
<output>80</output>

<gadget id="calculator">120 * 80</gadget>
<output>9_600</output>

<gadget id="calculator">100 * 60</gadget>
<output>6_000</output>

<gadget id="calculator">9_600 - 6_000</gadget>
<output>3_600</output>

<result>3_600</result>