A number of four different digits is formed with the help of the digits 1,2,3,4,5,6,7 in all possible ways. How many such numbers can be formed?

Explanation

To solve the problem of forming a four-digit number using the digits 1, 2, 3, 4, 5, 6, and 7, we will follow these steps:

### Step 1: Determine the number of digits available
We have a total of 7 different digits: 1, 2, 3, 4, 5, 6, and 7.

### Step 2: Choose the first digit
For the first digit (thousands place), we can choose any of the 7 digits.
- **Choices for the first digit:** 7 options
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