Answer:
it's third option the one who says 10 units up
The answer is a negative number so it cant be between 4 & 5
The answer is 5 x 4 x 3 x 2 x 1 or 5! (! = factorial)
It is a permutation, as the order matters.
There are 120 ways they can form a line.
You can use mental math to perform the following addition by knowing that certain numbers equal a certain number. for instance, you know that 9+2 is equal to 11. you don't need a calculator to solve that. then you know that 1+8 is equal to 9.since you are adding 11 you know that the answer is 19. you can use that to answer to following equation.
