Obviously when calculating ((1/2)+□)*(2/9), it becomes (1/2)+□*(2/9), how much is his calculation result greater than the original formula.
明明在计算((1/2)+□)*(2/9)时，算成了(1/2)+□*(2/9)，他的计算结果比原式大多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">(1/2) - (1/9)</gadget>
<output>7/18 = around 0.388889</output>

<result>7/18 = around 0.388889</result>