Factorials

key notes :

A whole number followed by an exclamation point is called a factorial. To evaluate a factorial, multiply all the whole numbers between 1 and the given number.

Learn with an example

➡️ Evaluate:

3! = ______

To evaluate 3!, multiply all the numbers between 1 and 3.

3!= 3 × 2 × 1

= 6

So, 3! = 6.

➡️ Evaluate:

5! = _____

To evaluate 5!, multiply all the numbers between 1 and 5.

5!= 5 × 4 × 3 × 2 × 1

= 120

So, 5! = 120.

➡️ Evaluate:

2! =_____

To evaluate 2!, multiply all the numbers between 1 and 2.

21 = 2 x 1

= 2

So, 2! = 2.

let’s practice!