How many centimeters of iron wire are needed to make a cuboid frame with a length of 8 cm, a width of 7 cm, and a height of 6 cm.
做一个长8厘米，宽7厘米，高6厘米的长方体框架需要铁丝多少厘米．
<gadget id="calculator">8 + 7 + 6</gadget>
<output>21</output>

<gadget id="calculator">21 * 4</gadget>
<output>84</output>

<result>84</result>