One row of eighteen people, eighteen rows of one person, nine rows of two people or two rows of nine people.
None. 2 pairs = 2*2 people So 4 rows of 2 pairs = 2*2*4 = 16 people. You have only 8.
2 rows of 24 3 rows of 16 4 rows of 12
You can have: 1 row of 36 2 rows of 18 3 rows of 12 4 rows of 9 or 6 rows of 6, so in total there are 5 ways.
24 ways
5040
90000
There are n! (n factorial) ways that n people can stand in line. So six people can stand in line in: 1*2*3*4*5*6 = 720 different ways
Two ways only. 4 rows with 25 stamps each or 5 rows with 20 stamps each.
720
If the people are always facing forward? 24 ways.
36