Divide a wire into two sections, the first section is three times the second section, then the length of the second section is the length of the iron wire.
把一根铁丝分成2段，第一段是第二段的3倍，则第二段的长度是这根铁丝的多少．
<gadget id="calculator">1 * 3</gadget>
<output>3</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>