请教PREP数学题

sumerlaws

A certain company has 18 equally qualified applicants for 4 open positions. How many different groups of 4 applicants can be chosen by the company to fill the positions if the order of selection does not matter?

答案是3060，我看不懂这道题什么意思哦向大家请教下

sumerlaws

谢谢，原来是这样的，看不懂题目真的无语了。看来要把那些数学术语过一遍了。

banglixing

这是一道组合题，不考虑4个人的次序，从18个人里选4个出来，一共的可能数是：
18*17*16*15
------------------  = 3060
       4！