A rope 2 meters long, use (1/3) first, and then use the rest (1/3), how many meters are left.
一根长2米的绳子，先用去(1/3)，再用去剩下的(1/3)，还剩下多少米．
<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 * (2/3) * (2/3)</gadget>
<output>8/9 = around 0.888889</output>

<result>8/9 = around 0.888889</result>