freeCodeCamp/curriculum/challenges/english/08-coding-interview-prep/project-euler/problem-383-divisibility-comparison-between-factorials.english.md

id	challengeType	title
5900f4ed1000cf542c50ffff	5	Problem 383: Divisibility comparison between factorials

Description

Let f5(n) be the largest integer x for which 5x divides n. For example, f5(625000) = 7.

Let T5(n) be the number of integers i which satisfy f5((2·i-1)!) < 2·f5(i!) and 1 ≤ i ≤ n. It can be verified that T5(103) = 68 and T5(109) = 2408210.

Find T5(1018).

Instructions

Tests

tests:
  - text: <code>euler383()</code> should return 22173624649806.
    testString: assert.strictEqual(euler383(), 22173624649806);

Challenge Seed

function euler383() {
  // Good luck!
  return true;
}

euler383();

Solution

// solution required