823543
Using your rule - essentially, it's the simplified sum of 9999999-2000000 which is a total of 7999999 numbers !
7
The first digit can be formed in 8 ways (excluding 0 and 1). The rest of the 6 digits each can be filled in 10 ways. The total number of digits, therefore is 8 x 10^6.
Oh, dude, let me break it down for you. So, since the first digit can't be 0 or 1, we have 8 options for that first digit. After that, we have 9 options for the next digit, then 8 for the next, and so on. So, it's like 8 x 9 x 8 x 7 x 6 x 5 x 4. Crunch those numbers and you get the total number of 7-digit phone numbers that can be formed without repeating any digits.
Assuming all digits are equally likely, then it is 0.9395.However, that assumption is flawed since some numbers begin with 0. Some sequences are reserved and so on. So the distribution of numbers is NOT truly random and the above answer depends on all seven digit numbers being equally likely..
Using your rule - essentially, it's the simplified sum of 9999999-2000000 which is a total of 7999999 numbers !
7
The first digit can be formed in 8 ways (excluding 0 and 1). The rest of the 6 digits each can be filled in 10 ways. The total number of digits, therefore is 8 x 10^6.
Oh, dude, let me break it down for you. So, since the first digit can't be 0 or 1, we have 8 options for that first digit. After that, we have 9 options for the next digit, then 8 for the next, and so on. So, it's like 8 x 9 x 8 x 7 x 6 x 5 x 4. Crunch those numbers and you get the total number of 7-digit phone numbers that can be formed without repeating any digits.
10 digit numbers
In the 1940s, phone numbers typically consisted of a three-digit area code followed by a seven-digit local number, such as "ABC-1234." This format differed from modern phone numbers, which generally have a three-digit area code followed by a seven-digit local number, such as "(123) 456-7890."
Without restrictions, it was would numbers 000-000-0000 through 999-999-9999. So that would be 9,999,999,999 + 1 = 10 billion different 10-digit phone numbers. Ex: If there existed single digit phone numbers, there would be 10, because the digits are 0 through 9. If there existed only double digit phone numbers, then it would be 00 through 99 which would be 100 total two-digit numbers. Therefore the total possible combinations for an X digit phone number would be: 10^X
A 4 digit pin is the last four numbers in your phone number.
A 4 digit pin is the last four numbers in your phone number.
Assuming all digits are equally likely, then it is 0.9395.However, that assumption is flawed since some numbers begin with 0. Some sequences are reserved and so on. So the distribution of numbers is NOT truly random and the above answer depends on all seven digit numbers being equally likely..
The first digit: 6
2020