Area codes for phone numbers are 3 digits long. How many different area codes can be made from the digits 0 through 9 if no digit is used more than once in any single area code? 27 30 720 1,000
For the first digit there are 10 options. For the second digit, the number used in the first digit can not be reused leaving 9 options. The third digit had 8 options.
