A four-digit serial number is to be created from the digits 0 through 9. How many of these serial numbers can be created if 0 can not be the first digit, no digit may be repeated, and the last digit must be 5?
For the answer to the question above, the 1st digit has 9 possible digits 2nd digit: 9 possible digits 3rd digit: 8 possible digits 4th digit: 1 possible digits (number 5 only) Number of serial numbers = 9 * 9 * 8 * 1 = 648 I hope this helps. Have a nice day ahead!
