Solve the problem.
-How many 4-digit numbers can be formed using the digits 0, 1, 2, 3, 4, 5, 6, if repetition of digits is not allowed?
A) 24
B) 2401
C) 23
D) 840

Question

Quizplus · Accepted Answer

For the first digit, we have 8 choices (any digit except for 0). For the second digit, we have 7 choices (any digit except for the one we picked for the first digit). Similarly, for the third digit, we have 6 choices, and for the fourth digit, we have 5 choices. Therefore, the total number of 4-digit numbers that can be formed is 8*7*6*5 = 840. There are 8 choices for the first digit, then 7 choices for the second digit (since we cannot repeat the first digit), then 6 choices for the third digit, and finally 5 choices for the fourth digit. Thus, the total number of 4-digit numbers is 8 x 7 x 6 x 5 = 840. Therefore, the answer is D.

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