Discussion
Four digit numbers are formed using 0, 3, 4, 5, 9, 8 without repetitions. Then the number of such 4 digits numbers is
Answer: B
There are 300 such numbers.
Six digits are available (0, 3, 4, 5, 9, 8), used without repetition, and a four digit number cannot start with 0.
\[ \begin{aligned} &\text{first digit: 5 choices (not 0)} \\ &\text{then } 5 \times 4 \times 3 = 60 \text{ for the rest} \\ &5 \times 60 = 300 \end{aligned} \]
Equivalently, all arrangements \(6 \times 5 \times 4 \times 3 = 360\), minus those starting with 0, \(5 \times 4 \times 3 = 60\), gives 300. 360 is not offered; 270 and the others come from miscounting the restriction on the first digit.
No comment is present. Be the first to comment.
Loading…
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development