Write numbers according to the law: (1/2), (1/3), (1/4), how much.
按规律写数：(1/2)、(1/3)、(1/4)、多少．
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

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

<result>1/5 = around 0.2</result>