Solve the problem.
-How many 3-digit numbers can be formed using the digits 1, 2, 3, 4, 5, 6, 7 if repetition of digits is not allowed?
A) 5
B) 343
C) 210
D) 6

Question

Quizplus · Accepted Answer

To form a 3-digit number, we have to choose a digit for the hundreds place, a digit for the tens place, and a digit for the units place. Since we cannot use the same digit more than once, we have 7 choices for the hundreds place, 6 choices for the tens place (since we used one digit already), and 5 choices for the units place (since we used two digits already). Therefore, the total number of 3-digit numbers that can be formed is 7*6*5 = 210.

Solve the Problem. -How Many 3-Digit Numbers Can Be Formed Using the Digits