# Phone numbers

How many 7-digit telephone numbers can be compiled from the digits 0,1,2,..,8,9 that no digit is repeated?

### Correct answer:

**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.

3 years ago 1 Like

Tips for related online calculators

#### You need to know the following knowledge to solve this word math problem:

## Related math problems and questions:

- How many 4

How many four-digit numbers that are divisible by ten can be created from the numbers 3, 5, 7, 8, 9, 0 such no digits repeats? - Three-digit numbers

How many are all three-digit numbers that are made up of digits 0,2,5,7 and are divisible by 9 if the digits can be repeated? - Numbers

How many different 3 digit natural numbers in which no digit is repeated can be composed of digits 0,1,2? - Double-digit 33471

How many double-digit numbers greater than 60 can we make from digits 0,5,6,7,8,9? The numerals must not be repeated. - Three-digit numbers

We have digits 0,1,4,7 that cannot be repeated. How many three-digit numbers can we write from them? You can help by listing all the numbers. - Digits

How many five-digit numbers can be written from numbers 0.3,4, 5, 7 that is divided by 10, and if digits can be repeated? - Two-digit 3085

How many two-digit numbers can you create from the digits 7,0,1 and 5 if the numerals can be repeated? - Dd 2-digit numbers

Find all odd 2-digit natural numbers compiled from digits 1; 3; 4; 6; 8 if the digits are not repeated. - Three-digit number

How many three-digit natural numbers can we form from the digits 0, 1, and 2 if the numerals can be repeated in these numbers? - Two-digit 17443

How many are all even two-digit numbers that We can create from the digits 2, 4, and 7? The numerals can be repeated in the created number. - Ascending 32663

How many natural numbers can you make from the digits in 4052? No digit may be repeated in the number entry. Sort the numbers in ascending order of size. - Telephone numbers

How many 7-digit telephone numbers can we put together so that each number consists of different digits? - How many

How many double-digit numbers greater than 30 we can create from digits 0, 1, 2, 3, 4, 5? Numbers cannot be repeated in a two-digit number. - Two-digit 64294

How many natural two-digit numbers can we form from the digits 0, 1, 2, 3 if the numerals cannot be repeated in these numbers? - Four-digit 73114

How many four-digit numbers can we assemble from the digits 2, 6, 3, 5, 1, and 9 if the numerals in the number cannot be repeated? - Permutations

How many 4-digit numbers can be composed of numbers 1,2,3,4,5,6,7 if: and the digits must not be repeated in the number b, the number should be divisible by five, and the numbers must not be repeated c, digits can be repeated - Repeated 38103

How many 5-digit numbers can we assemble from the numbers 2,3,4,5,6,7,8,9, if the digit in each number can be repeated only once?