A cake, father ate (1/8), mother ate (3/8), and the rest was eaten by Xiao Ming, how much Xiao Ming ate.
一个蛋糕，爸爸吃了(1/8)，妈妈吃了(3/8)，剩下的全部是小明吃的，小明吃了多少．
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">1 - (1/8) - (3/8)</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>