How many 4-letter code can be formed using the first 10 letters of the English alphabet, if no letter can be repeated?

Explanation

To solve the problem of how many 4-letter codes can be formed using the first 10 letters of the English alphabet without repeating any letter, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Total Letters Available**:
We have the first 10 letters of the English alphabet: A, B, C, D, E, F, G, H, I, J.

2. **Determine the Number of Positions**:
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