1. The problem statement, all variables and given/known data How many 4-digit patterns are there in which all the digits are different? 2. Relevant equations 10!/6! ?? 3. The attempt at a solution As shown above, I used 10!/6! and I get 5040. I get the same answer of course when I use 10x9x8x7. But my book shows the answer as 4536. What am I missing?