The number of five digit telephone numbers having at least one of their digits repeated is `90000` b. `100000` c. `30240` d. 69760

Options

A. 90000
B. 27216
C. 62784
D. 15120

Explanation

To solve the problem of finding the number of five-digit telephone numbers having at least one digit repeated, we can follow these steps:

### Step 1: Calculate the total number of five-digit telephone numbers
A five-digit telephone number can have digits from 0 to 9. Since there are no restrictions on the digits (including 0), each of the five positions in the number can be filled with any of the 10 digits.

- Total choices for each digit = 10
- Therefore, the total number of five-digit telephone numbers = \(10^5 = 100000\).

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