Now you have three choices:
Option 1: Guess and check. When you get to n = 10 you'll have the answer.
Option 2: By definition of the factorial, the equation can be written as
Therefore n = 10 (the negative solution is rejected).
Option 3: Note that . Therefore . This suggests that the left and right hand sides are equal to 7!. Hence n = 10. Check it ..... Correct.