# How many 7 digit phone numbers can be formed if the first digit Cannot be 0 and if no digit can be repeated?

## How many 7 digit phone numbers can be formed if the first digit Cannot be 0 and if no digit can be repeated?

544320 ways
Therefore, we have 544320 ways of seven-digit phone numbers can be formed if the first digit cannot be 0 and repetition of digits is not permitted.

How many phone numbers are possible with 7 digits?

So total number of 7 digit numbers=9999999 – 1000000+1). Out of 9000000 numbers, 4500000 are having the sum of digits as even and the remaining 4500000 are having the sum of digits as odd. Every alternate number has its sum of digits even and odd. There are 9000000 seven digit numbers.

### How many 7 digit numbers are there with no repetition allowed?

There are 9 digits you can have for the first digit (can’t have 0). There are then 9 more for the second (all except the first one). Similarly there are 8 for the third, 7 for the 4th, etc… So the total would be 9*9*8*7*6*5*4 = 544,320 7 digit numbers without repeated digits.

How many 7 digit numbers can be formed by using the numbers 1 2 and/or 3?

We know that the factorial can be written by the formula n! =n×(n−1)! Therefore, the number of different seven-digit numbers that can be written using only three digits 1,2 and 3 is 672. Thus, option (A) is the correct answer.

## What is a 7 digit phone number?

Unsourced material may be challenged and removed. Seven-digit dialing is a telephone dialing procedure customary in the territories of the North American Numbering Plan, for dialing telephone numbers in the local calling area. The procedure is also sometimes known as local format or network format.

What is a 7-digit phone number?

### Why do phone numbers have 7 digits?

Telephone engineers created a 7-digit system for “all number calling” to expand their pool of possible number combinations. Area codes were selected based on the population in that city, and the areas with the largest populations received codes that were easily dialed on a rotary phone.

How many 7 digit numbers are there having the digit 3 three times and the digit 0 four times )?

Latest Book Aptitude Question SOLUTION: How many 7 digit numbers are there having the digit 3 three times and the digit 0 four times. Ans :15.

## How many digits are used to number a book containing 300 pages?

so the final answer is 600 hope it helped…..

Are phone numbers always 7 digits?

All local numbers are now seven-digit, as the last technological hold-outs have given way to modern switching technology. The concept of a ten-digit local number is now conceived, as New York has an overlay code, but seven-digit dialing is still the norm.

### Why are phone numbers 7 digits?

What does 7 digits mean?

When we talk about 7-digit numbers, we mean the place values up to 1,000,000 or 10,00,000.

## How many possible telephone numbers are there with 7 blanks?

Think of seven blanks as seven digits of the telephone number. The first digit cannot be 0, so it can be filled by the other 8 digits. The remaining blanks can be filled by all 10 digits. So total number of possible telephone numbers are 8*10*10*10*10*10*10.

How many ways can you make a 7 digit phone number?

So the total number of ways in which 7-digit phone numbers are possible assuming that the first digit can’t be a 0 or a 1 are 8 * 10^6 = 8000000 including repetition. We have 7 digits to fill and 10 digits (0,1,2,3,4,5,6,7,8,9) to fill them out with. in a phone number, the digits are repeatable.

### What is the total number of possible telephone numbers?

The first digit cannot be 0, so it can be filled by the other 8 digits. The remaining blanks can be filled by all 10 digits. So total number of possible telephone numbers are 8*10*10*10*10*10*10. There are 9998976 possible numbers.

How many ways can a telephone number begin with 0?

We have to form 7 digit telephone numbers. Every digit can be filled with any one of these numbers in 5 ways. So, the noumber must end with 0. Fill the unit place with 0. This can be done in only one way. The number cannot begin with 0. This can be done in 9 ways. This can be done in 10 ways.