After adding the numerator and denominator of (1/4), it can be roughly divided into (4/5).
(1/4)的分子、分母同时加上多少后，约分为(4/5)．
<gadget id="calculator">4 / 1</gadget>
<output>4</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

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

<gadget id="calculator">(16/5) - 1</gadget>
<output>11/5 = around 2.2</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(11/5) / (1/5)</gadget>
<output>11</output>

<result>11</result>