Six
If only the order is interesting (not the direction that they are oriented) then In the first place there can be any of the three, in the second place there can be either of the two left and then the last place is a given so: 3 * 2 * 1 = 6
Six different orders for three people standing in a line.
If their direction is also interesting to take into account (e.g. the middle person facing north while the others face east) then you have to know how many different directions and if standing on their heads counts as different etc.
720
27!
6 ways. 3 x 2 x 1 = 6
There are 5040 ways.
ask someone els
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
5040
36
If the people are always facing forward? 24 ways.
Not sure what a strait line is! Five people can stand in a straight line, with Jessie third in 24 ways if you ignore left-to-right and right-to-left "reflections".
128
4*3*2*1 = 24 ways.
There are 7 people who could stand first, with 6 people who could stand second for each of those first people, with 5 people who could stand third for each of those first two people, and so on, until with 1 person left who could stand seventh for each of the first six people. This gives 7 × 6 × 5 × ... × 1 = 5040 ways.
I make it 136 ways.
24 ways
10 people can line up in (10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2) = 3,628,800 different ways.
720