For a square fish pond, if one group of opposite sides increases by 8 meters, then the area will increase by 216 square meters. How many square meters is this fish pond originally?
一个正方形的鱼塘，如果一组对边增加8米，那么面积就增加216平方米，这个鱼塘原来有多少平方米？
<gadget id="calculator">216 / 8</gadget>
<output>27</output>

<gadget id="calculator">27 * 27</gadget>
<output>729</output>

<result>729</result>