Question

How many 4 digit numbers. can be formed using the digits 1,2,3,4,5 if no digit is not repeated?

• A. 24
• B. 120
• C. 80
• D. 48

Answer 1

Answer:

B. 120

ones place can be filled in 5 ways. Since, repetition is not allowed, tens place can be filled by remaining 4 digits. So, there are 4 ways to fill ten's place. Since, repetition is not allowed , so hundreds place can be filled by remaining 3 digits . So, hundred's place can be filled in 3 ways. Similarly, to fill thousand's place, we have 2 digits remaining. So,thousand's place can be filled in 2 ways. So, required number of ways in which four digit numbers can be formed from the given digits is 5×4×3×2=120