Pour out (1/4) of a bottle of pure alcohol and fill it up with water, then pour out (1/5) and still fill it up with water, and then pour out (1/6) and then fill it up with water, at this time the pure alcohol in the bottle How much less than the original?
一瓶纯酒精倒出(1/4)后用水加满，再倒出(1/5)后仍用水加满，再倒出(1/6)后还用水加满，这时瓶中纯酒精比原来少几分之几？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(3/4) * (1/5)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 - (1/4) - (3/20)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(3/5) * (1/6)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/4) + (3/20) + (1/10)</gadget>
<output>1/2 = around 0.5</output>

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