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id	challengeType	title	forumTopicId
5900f3801000cf542c50fe93	5	Problem 20: Factorial digit sum	301839

Description

n! means n × (n − 1) × ... × 3 × 2 × 1 For example, 10! = 10 × 9 × ... × 3 × 2 × 1 = 3628800,
and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27. Find the sum of the digits n!

Instructions

Tests

tests:
  - text: <code>sumFactorialDigits(10)</code> should return 27.
    testString: assert.strictEqual(sumFactorialDigits(10), 27);
  - text: <code>sumFactorialDigits(25)</code> should return 72.
    testString: assert.strictEqual(sumFactorialDigits(25), 72);
  - text: <code>sumFactorialDigits(50)</code> should return 216.
    testString: assert.strictEqual(sumFactorialDigits(50), 216);
  - text: <code>sumFactorialDigits(75)</code> should return 432.
    testString: assert.strictEqual(sumFactorialDigits(75), 432);
  - text: <code>sumFactorialDigits(100)</code> should return 648.
    testString: assert.strictEqual(sumFactorialDigits(100), 648);

Challenge Seed

function sumFactorialDigits(n) {
  // Good luck!
  return n;
}

sumFactorialDigits(100);

Solution

// solution required

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