Question

All the odd numbers from 1 to 9 are written in every possible order. how many numbers can be formed if repetition is not allowed ?

Answer 1

Total odd numbers from 1 - 9 = 5   ( 1, 3 , 5 , 7 , 9 )

Since, the repetition is not allowed and there are 5 odd numbers from 1 - 9.

Therefore,

Numbers which can be formed without repetition = 5! = 5 x 4 x 3 x 2 x 1 = 120.

=> 120  numbers can be formed.