Calculation: (1/20)+(2/20)+(3/20)+...+(19/20).
计算：(1/20)+(2/20)+(3/20)+…+(19/20)．
<gadget id="calculator">1 + 19</gadget>
<output>20</output>

<gadget id="calculator">19 / 2</gadget>
<output>19/2 = around 9.5</output>

<gadget id="calculator">20 * (19/2)</gadget>
<output>190</output>

<gadget id="calculator">190 / 20</gadget>
<output>19/2 = around 9.5</output>

<result>19/2 = around 9.5</result>