(1/5) is used for 1 kg of nails, and (1/5) kg is used again, how many kilograms are used for the two times?
1千克铁钉用去(1/5)，又用去(1/5)千克，两次共用去多少千克．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 * (1/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) + (1/5)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>