A pillowcase is 6 decimeters long and 4 decimeters wide. If you put lace around it, how many decimeters of lace will you need at least?
一只枕套长6分米，宽4分米，如果在它的四周镶上花边，至少需要多少分米的花边．
<gadget id="calculator">6 + 4</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<result>20</result>