How many different numbers lesser than 10000 can be formed from the digits 0,1,3,6,8,7 and 9, if no digit is repeated ?

Explanation

To find out how many different numbers less than 10,000 can be formed from the digits 0, 1, 3, 6, 8, 7, and 9 without repeating any digit, we can break the problem down into four cases based on the number of digits in the numbers we can form: 1-digit, 2-digit, 3-digit, and 4-digit numbers.

### Step-by-Step Solution:

**Case 1: 1-Digit Numbers**
- The possible digits are: 1, 3, 6, 8, 7, 9 (0 cannot be used as a 1-digit number).
- Total 1-digit numbers = 6.

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