How to calculate factorials

Factorials , Mathematics
Hello ! everyone in this video, I will show how to calculate factorials ( n!).

n! = n x (n-1) x (n-2) x ... .2 x 1

Ex : 1! =1
2! = 2 x 1 = 2
3! = 3 x 2 x 1 = 6
4! = 4 x 3 x 2 x 1 = 24
5! = 5 x 4 x 3 x 2 x 1 =120

Manner of Factorials
10! = 10 x 9!
or 10! = 10 x 9 x 8!
or 10! = 10 x 9 x 8 x 7!
or 10! = 10 x 9 x 8 x 7 x 6!
or 10! = ... (other ways)

Operation of Factorials
Addition :
Ex : 2! + 3! = (2 x 1) + (3 x 2 x 1) = 2 + 6 = 8
Not : 2! + 3! = 5!
Subtraction :
Ex : 3! - 2! = (3 x 2 x 1) - (2 x 1) = 6 - 2 = 4
Not : 3! - 2! = 1!
Multiplication :
Ex : 2! x 3! = (2 x 1) x (3 x 2 x 1) = 2 x 6 = 12
Not : 2! x 3! = 6!^2
Division :
Ex : 4! / 2! = (4 x 3 x 2!) / (2!) = 4 x 3 = 12
Not : 4! x 2! = 2

Exercises for you to practice
a. 6! , b. 3! - 5!
c. (4 - 2)! , d. 2 x 3!
e. 4! / 6! , f. (4! x 3!) / 5!

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Channel : Hoeurng Ratha