A pile of sand, (1/2) was transported away for the first time, and the rest (1/4) was transported away for the second time, how much of this pile of sand is left
一堆沙子，第一次运走了(1/2)，第二次运走了剩下的(1/4)，还剩下这堆沙子的多少
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/2) * (1/4)</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">1 - (1/2) - (1/8)</gadget>
<output>3/8 = around 0.375</output>

<result>3/8 = around 0.375</result>