The last part of a telephone number has four digits, e.g.
7814 1487 2103 2772
The last part of the telephone number can start with any digit apart from zero.
The other three digits can be any number. How many four digit numbers are there?
10x10x10x9=?
To find the total number of four-digit telephone numbers, we need to consider the possible values for each digit in the number.
The first digit of the number can be any number from 1 to 9 since it cannot be zero.
The remaining three digits can be any number from 0 to 9 since there are no restrictions.
To calculate the total number of options for each digit, we multiply the possibilities for each digit together.
First digit: 9 options (as it cannot be zero)
Second digit: 10 options (from 0 to 9)
Third digit: 10 options (from 0 to 9)
Fourth digit: 10 options (from 0 to 9)
To find the total number of four-digit numbers, we multiply these options together:
9 x 10 x 10 x 10 = 9,000
Therefore, there are 9,000 four-digit telephone numbers.