How many numbers can be formed from the digits 1, 3, 5, 9

Question:

How many numbers can be formed from the digits 1, 3, 5, 9 if repetition of digits is not allowed?

 

Solution:

To find: number of numbers that can be formed from the digits 1, 3, 5, 9 if repetition of digits is not allowed

Forming a 4 digit number: $4 !$

Forming a 3 digit number: ${ }^{4} \mathrm{C}_{3} \times 3 !$

Forming a 2 digit number: ${ }^{4} \mathrm{C}_{2} \times 2 !$

Forming a 1 digit number: 4

So total number of ways $=4 !+\left({ }^{4} \mathrm{C}_{3} \times 3 !\right)+\left({ }^{4} \mathrm{C}_{2} \times 2 !\right)+4$

$=24+24+12+4$

$=64$

 

Leave a comment

Close

Click here to get exam-ready with eSaral

For making your preparation journey smoother of JEE, NEET and Class 8 to 10, grab our app now.

Download Now