If a square with a side length of 3 cm is enlarged at a ratio of 2:1, what is the area in square centimeters after the enlargement?
把边长3厘米的正方形，按2：1的比放大，放大后的面积是多少平方厘米．
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">6 * 6</gadget>
<output>36</output>

<result>36</result>