The sum of 4 0.1 and how many (1/10) is 1.
4个0.1与多少个(1/10)的和是1．
<gadget id="calculator">0.1 * 4</gadget>
<output>0.4</output>

<gadget id="calculator">1 - 0.4</gadget>
<output>0.6</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">0.6 / (1/10)</gadget>
<output>6</output>

<result>6</result>