Make a circle with (4/25) meters of iron wire. How many meters are left after making 20 circles with a section of 5-meter-long iron wire?
做一个圆圈用铁丝(4/25)米，有一段5米长的铁丝做20个圆圈后还剩多少米？
<gadget id="calculator">4 / 25</gadget>
<output>4/25 = around 0.16</output>

<gadget id="calculator">(4/25) * 20</gadget>
<output>16/5 = around 3.2</output>

<gadget id="calculator">5 - (16/5)</gadget>
<output>9/5 = around 1.8</output>

<result>9/5 = around 1.8</result>