A cup of milk is 1000ml. Xiao Ming drank half a cup for the first time, then filled up the coffee, drank this cup (1/3) for the second time, filled up the coffee again, and drank this cup (1/3) for the third time 4) Refill the coffee, how many milliliters of milk is there in the cup?
一杯牛奶1000毫升，小明第一次喝了半杯，然后加满咖啡，第二次喝了这杯的(1/3)，再加满咖啡，第三次又喝了这杯的(1/4)，再加满咖啡，这时杯内还有多少毫升的牛奶？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) * (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 - (1/2) - (1/6)</gadget>
<output>1/3 = around 0.333333</output>

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

<gadget id="calculator">(1/3) * (1/4)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 - (1/2) - (1/6) - (1/12)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1_000 * (1/4)</gadget>
<output>250</output>

<result>250</result>