To make a glass counter with a length of 20dm, a width of 4dm, and a height of 8dm, it is necessary to install angle irons on each side of the counter, how many angle irons are needed in dm.
做一个长20dm、宽4dm、高8dm的玻璃柜台，要在柜台各边安上角铁，需要角铁多少dm．
<gadget id="calculator">20 + 4 + 8</gadget>
<output>32</output>

<gadget id="calculator">32 * 4</gadget>
<output>128</output>

<result>128</result>