# A calculus of the absurd

### Chapter 16 Combinatorics

#### 16.1 Basic counting principles

##### 16.1.1 Finding the number of permutations

How many ways can we arrange distinct people in a straight line? For $$n$$ people in a straight line, we can put $$n$$ people in the first position, $$n-1$$ people in the second position, $$n-2$$ in the third, and so on. Overall, then the number of ways of arranging distinct people in a line is equal to

$$(n)(n-1)(n-2)...1 = n!$$

TODO