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---
id: 5900f45c1000cf542c50ff6e
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title: 'Problem 239: Twenty-two Foolish Primes'
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challengeType: 5
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forumTopicId: 301884
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dashedName: problem-239-twenty-two-foolish-primes
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---
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# --description--
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A set of disks numbered 1 through 100 are placed in a line in random order.
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What is the probability that we have a partial derangement such that exactly 22 prime number discs are found away from their natural positions? (Any number of non-prime disks may also be found in or out of their natural positions.)
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Give your answer rounded to 12 places behind the decimal point in the form 0.abcdefghijkl.
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# --hints--
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`euler239()` should return 0.001887854841.
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```js
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assert.strictEqual(euler239(), 0.001887854841);
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```
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# --seed--
## --seed-contents--
```js
function euler239() {
return true;
}
euler239();
```
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# --solutions--
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```js
// solution required
```