排列与組合数的計算在很多方面都有应用,中学教材中对不重复的排列数与組合数有了初步的討論。本文将討論某些更一般的排列与組合問題。在討論这些公式中,也适当介紹一些方法,即在§1,§2中介紹直接数个数的方法,在§3中簡单地介紹一下某些組合数的递推公式以及应用这些公式来求組合数的方法, The calculation of permutation and combinatorial numbers has applications in many aspects. There is a preliminary discussion of the number of non-repeated permutations and the number of combinations in high school textbooks. This article will discuss some of the more general permutations and combinations. In the discussion of these formulas, some methods are also properly introduced. That is, in §1, §2, the method of direct number is introduced. In §3, the recursive formulas of some combination numbers are briefly introduced and the formulas are applied. How to find the number of combinations,