If the length of a rectangle of 2 cm is doubled, but the width remains the same, how many centimeters will the perimeter of the rectangle be?
长2厘米的长方形的长增加到原来的2倍，宽不变，长方形的周长比原来多多少厘米
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<result>4</result>