The denominator is the largest true fraction of 10, subtract its fractional unit, what is the result?
分母是10的最大真分数，减去它的分数单位，结果是多少．
<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(9/10) - (1/10)</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>