We need to determine how many numbers between 1 and 1000 (both inclusive) have at least one repeated digit.
Step 1: Total numbers from 1 to 1000
- There are 1000 numbers.
Step 2: Count numbers with no repeated digits and subtract from 1000
(A) 1-digit numbers (1 to 9)
- There are 9 numbers (1 to 9). All have unique digits.
(B) 2-digit numbers (10 to 99)
- The tens digit can be any digit from 1 to 9 (9 choices).
- The ones digit can be any digit from 0 to 9 except the tens digit (9 choices).
- Total: 9 × 9 = 81 numbers.
(C) 3-digit numbers (100 to 999)
- The hundreds digit can be any digit from 1 to 9 (9 choices).
- The tens digit can be any digit from 0 to 9 except the hundreds digit (9 choices).
- The ones digit can be any digit from 0 to 9 except the two already chosen (8 choices).
- Total: 9 × 9 × 8 = 648 numbers.
(D) 4-digit number (1000)
- Only one number, 1000, which has repeated digits (three 0's).
Total numbers with unique digits = 9 + 81 + 648 = 738.
Step 3: Count numbers with repeated digits
- Numbers with repeated digits = Total numbers (1000) − Numbers with unique digits (738) = 262.
Conclusion
Answer: C (262 numbers have at least one repeated digit).