Elementary combinatorics: Factorial and binomial coefficient
Factorial
You use \(3\) different digits from \(\{1,\ldots, 9\}\) and make a number with it.
For example, with \(1, 3, 4\) you can form the number \(431\).
How many different numbers can you write down with the given \(3\) digits
| amount of numbers that can be written down = |
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