A letter lock consists of three rings each marked with 10 different letters. In how many ways it is possible to make an unsuccessful attempt to open the lock?

Explanation

To solve the problem of how many unsuccessful attempts can be made to open a letter lock consisting of three rings, each marked with 10 different letters, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Structure of the Lock**:
- The lock has 3 rings.
- Each ring has 10 different letters.

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