Question 52
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How many 4-digit numbers have at least one repeated digit?
- A 4,536
- B 5,040
- C 4,464 Correct
- D 3,168
Correct Answer: Option C
All 4-digit numbers: 9,000
All digits different: 9 × 9 × 8 × 7 = 4,536
9,000 − 4,536 = 4,464
Trap: 4,536 is the all-different count.
Answer: 4,464
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