The notation called
factorial notation is used in probability. Factorial notation uses the
exclamation mark or point and it involves multiplication. For instance,
4! = 4 • 3 • 2 • 1 = 24
3! = 3 • 2 • 1 = 6
2! = 2 • 1 = 2
1! = 1
In general, a factorial
is evaluated as follows:
n!
= n (n – 1) (n – 2) • • • 3 • 2
• 1 NB: the factorial is the product
of n factors, with the number decrease by 1 for each factor.
Properties:
1. One
property of factorial notation is that it can be stopped at any point by using
the exclamation point or mark. For example,
7! = 7 • 6! Since 6! = 6 • 5 • 4 • 3 • 2 • 1
= 7 • 6 • 5! Since 5!
= 5 • 4 • 3 • 2 • 1
= 7 • 6 • 5 • 4! Since 4! =
4 • 3 • 2 • 1
•
•
•
= 7 • 6 • 5 • 4 • 3 • 2 • 1
Thus,
n! = n (n - 1)!
= n (n - 1) (n - 2)!
= n (n - 1) (n - 2) (n - 3)! etc.
2.
Another
property of factorials is 0! = 1, this fact is needed for formulas.
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For any further advice on your studies or any challenge on this post, please feel free to contact me at: dzaazo@gmail.com. I will appreciate it.