43 lines
923 B
Markdown
43 lines
923 B
Markdown
---
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id: 5900f3fd1000cf542c50ff10
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title: 'Problem 145: How many reversible numbers are there below one-billion?'
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challengeType: 5
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forumTopicId: 301774
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dashedName: problem-145-how-many-reversible-numbers-are-there-below-one-billion
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---
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# --description--
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Some positive integers n have the property that the sum \[ n + reverse(n) ] consists entirely of odd (decimal) digits. For instance, 36 + 63 = 99 and 409 + 904 = 1313. We will call such numbers reversible; so 36, 63, 409, and 904 are reversible. Leading zeroes are not allowed in either n or reverse(n).
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There are 120 reversible numbers below one-thousand.
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How many reversible numbers are there below one-billion (109)?
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# --hints--
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`euler145()` should return 608720.
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```js
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assert.strictEqual(euler145(), 608720);
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```
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# --seed--
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## --seed-contents--
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```js
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function euler145() {
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return true;
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}
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euler145();
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```
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# --solutions--
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```js
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// solution required
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```
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