crack it

[chintz]

How many 9 digit number of different digits can be formed ?????

[attrc]

9x10^8

[arjmen]

1st digit can be any of 1 to 9 (can't be 0 ,since then the number wouldn't be a 9-digit number. Assuming of course that we're looking to form actual numbers and not just a 9-digit code)

2nd digit can be any of 9: 1 less than 0 to 9 to account for the 1st digit
3rd digit can be any of 8, 4th can be any of 7 etc..

Total number of 9-digit numbers that have different digits that exist = 9*9!
Too lazy to calculate.

[babra]

u dint mention with or with out repitition
if its with repitition then the answer.will be 9*10^8

[samy_dg]

Repititions are not allowed. The digits are said to be different; isn't it?

[babra]

okkkkk........ got it

[econphd123]

then it's 10*9*8*7*6*5*4*3*2 = 10!

[kunal227]

the answer is 9*9!

[econphd123]

Sorry, I see your point now. Forgot about zero It should be 9*9!