6 npr 1

This is not 6P1

It is 6P6

that is, in how many ways can 6 people be ordered if they are taken from an original group of 6 people.

$${\left({\frac{{\mathtt{6}}{!}}{({\mathtt{6}}{\mathtt{\,-\,}}{\mathtt{6}}){!}}}\right)} = {\mathtt{720}}$$

Note there are 6 ways to choose the first person in line, 5 ways to choose the second person in line, etc. So, the product of all these is just

6 x 5 x 4 x 3 x 2 x 1 = 6! = 720 ways

The 6! is read as "six factorial."  It represents the product of all the positive integers less than or equal to 6.