Use 4 small squares with side lengths of 2 cm to form a large square. What is the area of this square in square centimeters?
用4个边长是2厘米的小正方形，拼成一个大正方形，这个正方形的面积是多少平方厘米．
<gadget id="calculator">2 + 2</gadget>
<output>4</output>

<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<result>16</result>