Answer: 3628800
Step-by-step explanation:
There are 10 letters listed.
We have 10 choices for the first slot, then 9 for the next, and so on until reaching 1 choice for the tenth slot. Multiply that countdown of values to get the final answer.
10*9*8*7*6*5*4*3*2*1 = 3628800
For more information, search out "factorials". A related idea is "permutations".