LIST AS MANY COMBINATIONS POSSIBLE PLEASE!?

Question

Please list as many combinations you can using the letters - DD44FCMRFBS951HZY 

The fourth letter is D 
The tenth letter is D 
The last (seventeenth) letter is 4 



_ _ _ D _ _ _ _ _ D _ _ _ _ _ _ 4

Answer 1

There are 14 blank spaces.

Therefore 14 blank spaces can be replaced with 14 letters in 14! ways.

Letter F is repeated.

So number of arrangements = 14! / 2! =  87178291200 / 2 = 43,589,145,600 ways.