set of school uniform is 50 yuan. There are 56 students in Class 4 and Class 2. Each of them bought a school uniform. Teacher Wang has already collected 900 yuan. How many students have not paid?
一套校服50元四2班共有56名学生，每人买1套校服，王老师已经收了900元，还有多少名学生没有交钱？
<gadget id="calculator">900 / 50</gadget>
<output>18</output>

<gadget id="calculator">56 - 18</gadget>
<output>38</output>

<result>38</result>