Question

Seven digit number without repetition and divisible by 9 is to be formed by using 7 digits out of 1,2,3,4,5,6,7,8,9. the number of ways in which this can be done is

Answer 1

The divisibility of 9 is the sum of digits divisible by 9 .As the seven digit number is asked eliminating any two numbers whose sum is 9 .And arranging remaining numbers in order is divisible by 9.
Ex:2345678,1345679,1245689 etc