1.1 KiB
1.1 KiB
| id | title | challengeType | forumTopicId | dashedName |
|---|---|---|---|---|
| 5900f3c81000cf542c50fedb | Problem 92: Square digit chains | 5 | 302209 | problem-92-square-digit-chains |
--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
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?
--hints--
squareDigitChains() should return a number.
assert(typeof squareDigitChains() === 'number');
squareDigitChains() should return 8581146.
assert.strictEqual(squareDigitChains(), 8581146);
--seed--
--seed-contents--
function squareDigitChains() {
return true;
}
squareDigitChains();
--solutions--
// solution required