SOLUTION: How many different 5 digit codes are possible using the keypad show ,if the frist digit cannot be 0 and no digit may be use more than one?

Algebra ->  Probability-and-statistics -> SOLUTION: How many different 5 digit codes are possible using the keypad show ,if the frist digit cannot be 0 and no digit may be use more than one?      Log On


   



Question 391386: How many different 5 digit codes are possible using the keypad show ,if the frist digit cannot be 0 and no digit may be use more than one?
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
five digit codes using 10 digits, first one can't be 0
think of choices per digit - they can%27t repeat, so one digit is used each time
9+%2A+9+%2A+8+%2A+7+%2A+6=27216

Well, basically all you do in this problem is multiply.

- put down 5 blank spaces on paper and then put the number of combinations in each space.
For example, there are 10 total digits that can be used (0-9).
However the first digit can not be 0, so there are 9 possible combinations (1-9).
The second digit cannot be the same as the first digit, but it can be 0, so there are 9 combinations.
The third digit cannot be either the first or the second digit and thus there are 8 combinations.
The fourth digit has 7 combinations and the fifth has 6+combinations. so if you multiply the
numbers of combinations you should have
9+x+9+x+8+x+7+x+6+=+27216