4*(﹙1+0.2-1+0.2﹚/0.4)=how much
4*(﹙1+0.2-1+0.2﹚/0.4)=多少
<gadget id="calculator">0.2 + 0.2</gadget>
<output>0.4</output>

<gadget id="calculator">0.4 / 0.4</gadget>
<output>1</output>

<gadget id="calculator">4 * 1</gadget>
<output>4</output>

<result>4</result>