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curriculum/challenges/italian/10-coding-interview-prep/project-euler/problem-469-empty-chairs.md

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+---
+id: 5900f5411000cf542c510053
+title: 'Problem 469: Empty chairs'
+challengeType: 5
+forumTopicId: 302144
+dashedName: problem-469-empty-chairs
+---
+
+# --description--
+
+In a room N chairs are placed around a round table.
+
+Knights enter the room one by one and choose at random an available empty chair.
+
+To have enough elbow room the knights always leave at least one empty chair between each other.
+
+When there aren't any suitable chairs left, the fraction C of empty chairs is determined. We also define E(N) as the expected value of C. We can verify that E(4) = 1/2 and E(6) = 5/9.
+
+Find E(1018). Give your answer rounded to fourteen decimal places in the form 0.abcdefghijklmn.
+
+# --hints--
+
+`euler469()` should return 0.56766764161831.
+
+```js
+assert.strictEqual(euler469(), 0.56766764161831);
+```
+
+# --seed--
+
+## --seed-contents--
+
+```js
+function euler469() {
+
+  return true;
+}
+
+euler469();
+```
+
+# --solutions--
+
+```js
+// solution required
+```