There are 48 students in a class, 27 of whom can swim, 33 can ride a bicycle, and 40 can play table tennis. So, at least how many students in this class can play these three sports.
某班共有学生48人，其中27人会游泳，33人会骑自行车，40人会打乒乓球．那么，这个班至少有多少个学生这三项运动都会．
<gadget id="calculator">48 - 27</gadget>
<output>21</output>

<gadget id="calculator">48 - 33</gadget>
<output>15</output>

<gadget id="calculator">48 - 40</gadget>
<output>8</output>

<gadget id="calculator">21 + 15 + 8</gadget>
<output>44</output>

<gadget id="calculator">48 - 44</gadget>
<output>4</output>

<result>4</result>