A pillowcase is 5 decimeters long and 3 decimeters wide. If there is lace around it, how many decimeters of lace is needed at least?
一只枕套长5分米，宽3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">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<result>16</result>