In a mathematics competition, among the students (1/7) won the first prize, (1/3) won the second prize, (1/2) won the third prize, and the rest won the commemorative prize. It is known that there are less than 50 students participating in this competition. How many of them won the commemorative award?
一次数学竞赛，结果学生中(1/7)获得一等奖，(1/3)获得二等奖，(1/2)获得三等奖，其余获纪念奖．已知参加这次竞赛的学生不满50人，问获纪念奖的有多少人？
<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>