Question

The number greater than or equal to 1000 but less than or equal to 4000 is formed using the digits 0, 1, 2, 3, 4 (repetition allowed) is

• A. 125
• B. 105
• C. 375
• D. 625

Answer 1

The correct option is C 375

We are given the fact that the number is greater than 1000 and less than 4000. So the first digit can be 1 or 2 or 3. Three ways to fill the first digit.
Now what about the next three digits? Are there any constraints on those digits when repetitions are allowed? No. So the next three digits can be filled in five ways each.

Required number of numbers $=3\times 5\times 5\times 5=375$