A square has 10 people on each side of the outermost layer, how many people are there in the outermost layer?
一个方阵，最外层每边有10人，最外层一共有多少人．
<gadget id="calculator">10 * 4</gadget>
<output>40</output>

<gadget id="calculator">40 - 4</gadget>
<output>36</output>

<result>36</result>