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freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-383-divisibility-comparison-between-factorials.md
gikf d269909faa fix(curriculum): clean-up Project Euler 381-400 (#43024)
* fix: clean-up Project Euler 381-400

* fix: missing image extension

* fix: missing subscripts

Co-authored-by: Tom <20648924+moT01@users.noreply.github.com>

Co-authored-by: Tom <20648924+moT01@users.noreply.github.com>
2021-07-30 07:59:29 -07:00

918 B

id, title, challengeType, forumTopicId, dashedName
id title challengeType forumTopicId dashedName
5900f4ed1000cf542c50ffff Problem 383: Divisibility comparison between factorials 5 302047 problem-383-divisibility-comparison-between-factorials

--description--

Let f_5(n) be the largest integer x for which 5^x divides n.

For example, f_5(625\\,000) = 7.

Let T_5(n) be the number of integers i which satisfy f_5((2 \times i - 1)!) &lt; 2 \times f_5(i!) and 1 ≤ i ≤ n.

It can be verified that T_5({10}^3) = 68 and T_5({10}^9) = 2\\,408\\,210.

Find T_5({10}^{18}).

--hints--

factorialDivisibilityComparison() should return 22173624649806.

assert.strictEqual(factorialDivisibilityComparison(), 22173624649806);

--seed--

--seed-contents--

function factorialDivisibilityComparison() {

  return true;
}

factorialDivisibilityComparison();

--solutions--

// solution required