The side length of a square is 3 cm. If the side length is enlarged by 3:1, what is the area after the enlargement?
一个正方形边长是3厘米，如果边长按3：1扩大，放大后的面积是多少平方厘米．
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">9 * 9</gadget>
<output>81</output>

<result>81</result>