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

1.	How many numbers can be formed from the digits 1, 3, 5, 9 if repetition of digits is not allowed?
Answer» 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: 4C3 × 3! Forming a 2 digit number: 4C2 × 2! Forming a 1 digit number:4 So total number of ways = 4! + ( 4C3 × 3!) + (4C2 × 2!) + 4 = 24 + 24 + 12 + 4 = 64

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

Answer»

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: 4C3 × 3!

Forming a 2 digit number: 4C2 × 2!

Forming a 1 digit number:4

So total number of ways = 4! + ( 4C3 × 3!) + (4C2 × 2!) + 4

= 24 + 24 + 12 + 4

= 64