Solve the problem.
-How many 4-digit numbers can be formed using the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, if repetitions of digits are allowed?
A) 256
B) 10,000
C) 9999
D) 24

Question

Quizplus · Accepted Answer

Since repetitions are allowed, any of the 10 digits (0-9) can be used for each of the 4 places in the number. However, the first digit cannot be 0 (to ensure it's a 4-digit number), leaving 9 choices for the first digit and 10 choices for each of the remaining 3 digits. Therefore, the total number of 4-digit numbers is 9 * 10 * 10 * 10 = 9,000.

Solve the Problem. -How Many 4-Digit Numbers Can Be Formed Using the Digits