Question

Four persons enter a railway carriage in which there are six seats; in how many ways can they take their places?

Answer 1

There are $6$ possibilities for the first person to choose the place; and then the second person can select in $5$ ways; the third in $4$; and the fourth in $3$; and since each of these ways may be associated with each of the others, the required answer is $6\times 5\times 4\times 3$ or $360$.