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?
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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) (Show Source):
You can put this solution on YOUR website! digit codes using digits, first one can't be
think of choices per digit - they repeat, so one digit is used each time
Well, basically all you do in this problem is multiply.
- put down blank spaces on paper and then put the number of combinations in each space.
For example, there are total digits that can be used (0-9).
However the digit can not be , so there are possible combinations (1-9).
The digit cannot be the same as the first digit, but it can be , so there are combinations.
The digit cannot be either the first or the second digit and thus there are combinations.
The digit has combinations and the fifth has combinations. so if you multiply the
numbers of combinations you should have