freeCodeCamp/problem-92-square-digit-chains.english.md at 908adc2c372f2c1af0c8d1c80b264c23f96fd7d7

mrugesh 22afc2a0ca feat(learn): python certification projects (#38216 )

Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>
Co-authored-by: Kristofer Koishigawa <scissorsneedfoodtoo@gmail.com>
Co-authored-by: Beau Carnes <beaucarnes@gmail.com>

2020-05-27 13:19:08 +05:30

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id, challengeType, isHidden, title, forumTopicId

id	challengeType	isHidden	title	forumTopicId
5900f3c81000cf542c50fedb	5	false	Problem 92: Square digit chains	302209

Description

A number chain is created by continuously adding the square of the digits in a number to form a new number until it has been seen before.

For example,

44 → 32 → 13 → 10 → 1 → 1
85 → 89 → 145 → 42 → 20 → 4 → 16 → 37 → 58 → 89

Therefore any chain that arrives at 1 or 89 will become stuck in an endless loop. What is most amazing is that EVERY starting number will eventually arrive at 1 or 89.

How many starting numbers below ten million will arrive at 89?

Instructions

Tests

tests:
  - text: <code>squareDigitChains()</code> should return a number.
    testString: assert(typeof squareDigitChains() === 'number');
  - text: <code>squareDigitChains()</code> should return 8581146.
    testString: assert.strictEqual(squareDigitChains(), 8581146);

Challenge Seed

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

squareDigitChains();

Solution

// solution required

1.4 KiB Raw Blame History