How many 4-digit numbers can be formed using digits 1, 2, 3, 4, 5 without repetition?
Q1. How many 4-digit numbers can be formed using digits 1, 2, 3, 4, 5 without repetition?
Answer: 120
Explanation: Using permutation formula for 5 digits taken 4 at a time, P(5,4) = 5! / (5-4)! = 120.