The number of students in a certain class does not exceed 50, and (1/3) students get excellent, (1/7) students get good, and (1/2) students pass the standard, how many people fail?
某班人数不超过50人，一次体育达标中有(1/3)得优，(1/7)得良，(1/2)学生及格，那么不及格的有多少人．
<gadget id="calculator">3 * 7 * 2</gadget>
<output>42</output>

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

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

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

<gadget id="calculator">1 - (1/3) - (1/7) - (1/2)</gadget>
<output>1/42 = around 0.02381</output>

<gadget id="calculator">42 * (1/42)</gadget>
<output>1</output>

<result>1</result>