Use the factorial of 6 to find this solution. Namely, 6!
This means 6*5*4*3*2*1 which equals 720
It seems like a huge number, right? But think of it like this: For the first option, you have 6 collars. After you fill the first spot with one of the 6, you have 5 left that will fill the second spot. After the first 2 spots are filled and you used 2 of the 6 collars, there are 4 possibilities that can fill the next spot, etc.
Let the number of collectible dolls she can buy be x.
x ≤ 45/2.5
x ≤ 18
-------------------------------------------------------------------- Answer:She can buy at most 18 dolls. --------------------------------------------------------------------
