Uncle Zhang is going to use a bamboo fence to surround a rectangular vegetable field with a length of 8 meters and a width of 5 meters. How many meters of bamboo fence is needed at least?
张大爷准备用竹篱笆，靠一面墙围一个长8米，宽5米的长方形菜地，至少需要竹篱笆多少米？
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">8 + 10</gadget>
<output>18</output>

<result>18</result>