Maths-
General
Easy
Question
The number of five-digit telephone numbers having at least one of their digits repeated is
- 90000
- 100000
- 30240
- 69760
The correct answer is: 69760
The number of five-digit telephone numbers which can be formed using the digits 0, 1, 2 ….9 is 105 . The number of five-digit telephone number which have none of their digits repeated is 10P5 = 30240. Thus, the required number of telephone number is 105 – 30240 = 69760.
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