After subtracting how many (1/2) consecutively from 20, the result is (1/2).
从20里面连续减去多少个(1/2)后，结果得(1/2)．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">20 - (1/2)</gadget>
<output>39/2 = around 19.5</output>

<gadget id="calculator">(39/2) / (1/2)</gadget>
<output>39</output>

<result>39</result>