Let A = { 0 , 1 , 2 , 3 , … 9 } be a set consisting of different digits. The number of ways in which a nine digit number can be made in which, 1 and 2 are present and 1 is always ahead of 2 and repeti

Question

Let A = { 0 , 1 , 2 , 3 , … 9 } be a set consisting of different digits. The number of ways in which a nine digit number can be made in which, 1 and 2 are present and 1 is always ahead of 2 and repetition of digits is not allowed.

TestHub · Accepted Answer

2 9 P 2 8 ​ P 7 ​ − 7 C 1 ​ × 8 ! ​ 2 1 ​ ( Number of permutations in which 0 occupies first place and containing 1&2 Total number of permutations of nine numbers in which 1&2 are present − ​ )

Mathematics - Permutation & Combination Question with Solution | TestHub

Options:

Doubts & Discussion