15 round nails weigh about 10 grams, and how many round nails weigh about 20 grams.
15个圆钉大约重10克，多少个圆钉大约重20克．
<gadget id="calculator">10 / 15</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">20 / (2/3)</gadget>
<output>30</output>

<result>30</result>