# Phone numbers

How many 9-digit telephone numbers can be compiled from the digits 0,1,2,..,8,9 that no digit is repeated?

N =  3628800

### Step-by-step explanation:

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Showing 1 comment:
Mathyu
Solution is not correct. 0-9 is 10 digits, so n = 10 * 9 * 8 * 7 * 6 * 5 * 4 = 604800. Or, 10!/3! = 604800. If there was a restriction on the first digit, such that the first digit could not be 0 or 1, or any other number, then it would be 9. However, there is no restriction (that is given) to make this valid, so for the first digit, there are initially 10 digits to choose from. After one is taken, then it goes to 9 and etc.

5 years ago  4 Likes

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The passage contains a mathematical question about the number of unique 9-digit telephone numbers that can be created from the digits 0-9, and it provides an answer to this question.
single_question_with_answer
Given a text passage, determine:
    1. If it contains a mathematical question (including word problems or calculations)
    2. If an answer to that mathematical question is provided in the text

First, describe the content structure you found in 1-2 sentences.

Then provide your analysis in the following format:
TYPE: <one of the following values>
- NO_QUESTION
- SINGLE_QUESTION
- SINGLE_QUESTION_WITH_ANSWER
- MULTIPLE_QUESTIONS
- MULTIPLE_QUESTIONS_WITH_ANSWERS
system
# Phone numbers

How many 9-digit telephone numbers can be compiled from the digits 0,1,2,..,8,9 that no digit is repeated?

N =  3628800

### Step-by-step explanation:

Did you find an error or inaccuracy? Feel free to write us. Thank you!

Showing 1 comment:
Mathyu
Solution is not correct. 0-9 is 10 digits, so n = 10 * 9 * 8 * 7 * 6 * 5 * 4 = 604800. Or, 10!/3! = 604800. If there was a restriction on the first digit, such that the first digit could not be 0 or 1, or any other number, then it would be 9. However, there is no restriction (that is given) to make this valid, so for the first digit, there are initially 10 digits to choose from. After one is taken, then it goes to 9 and etc.

5 years ago  4 Likes

Tips for related online calculators
user
The passage contains a mathematical question about the number of unique 9-digit telephone numbers that can be created from the digits 0-9, and it provides an answer to this question.
TYPE: SINGLE_QUESTION_WITH_ANSWER