freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-148-exploring-pascals-triangle.english.md

id, challengeType, title, forumTopicId

id	challengeType	title	forumTopicId
5900f4021000cf542c50ff14	5	Problem 148: Exploring Pascal's triangle	301777

Description

We can easily verify that none of the entries in the first seven rows of Pascal's triangle are divisible by 7:

            1
          1   1
        1   2   1
      1   3   3   1
    1   4   6   4   1
  1   5   10  10  5   1
1   6   15  20  15  6   1

However, if we check the first one hundred rows, we will find that only 2361 of the 5050 entries are not divisible by 7.

Instructions

Find the number of entries which are not divisible by 7 in the first one billion (10⁹) rows of Pascal's triangle.

Tests

tests:
  - text: <code>euler148()</code> should return 2129970655314432.
    testString: assert.strictEqual(euler148(), 2129970655314432);

Challenge Seed

function euler148() {
  // Good luck!
  return true;
}

euler148();

Solution

// solution required