The number of students in a class does not exceed 60, and the test scores are divided into four grades: excellent, good, pass and fail. It is known that there are (1/7) students in this class who get excellent, (1/3) students get good, and (1/2) students pass, how many students in this class fail.
某班学生人数不超过60人，一次测验成绩分为优、良、及格和不及格四等．已知这次测验该班有(1/7)学生得优，(1/3)的学生得良，(1/2)的学生及格，则该班不及格的学生有多少人．
<gadget id="calculator">2 * 3 * 7</gadget>
<output>42</output>

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

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

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

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

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

<result>1</result>