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 10^{5} . The number of five-digit telephone number which have none of their digits repeated is ^{10}P_{5} = 30240. Thus, the required number of telephone number is 10^{5} – 30240 = 69760.

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