Question 16.
How many integers in the set {100, 101, 102, ..., 999} have at least one digit repeated?
A
B
C
D
Question Explanation
Text ExplanationVideo Explanation
Total number of numbers from 100 to 999 = 900
The number of three digits numbers with unique digits:
_ _ _
The hundredth's place can be filled in 9 ways ( Number 0 cannot be selected)
Ten's place can be filled in 9 ways
One's place can be filled in 8 ways
Total number of numbers = 9*9*8 = 648
Number of integers in the set {100, 101, 102, ..., 999} have at least one digit repeated = 900 - 648 = 252
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