Drink down (1/3) of a glass of water, and then drink the rest (2/3), how much water is left in the glass
一杯水喝下去(1/3)，又喝下去余下的(2/3)，这时杯中的水还剩多少
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(2/3) * (1/3)</gadget>
<output>2/9 = around 0.222222</output>

<result>2/9 = around 0.222222</result>