977 B
977 B
id | title | challengeType | forumTopicId | dashedName |
---|---|---|---|---|
5900f3fd1000cf542c50ff10 | Problem 145: How many reversible numbers are there below one-billion? | 5 | 301774 | problem-145-how-many-reversible-numbers-are-there-below-one-billion |
--description--
Some positive integers n
have the property that the sum [ n + reverse(n)
] consists entirely of odd (decimal) digits. For instance, 36 + 63 = 99
and 409 + 904 = 1313
. We will call such numbers reversible; so 36, 63, 409, and 904 are reversible. Leading zeroes are not allowed in either n
or reverse(n)
.
There are 120 reversible numbers below one-thousand.
How many reversible numbers are there below one-billion ({10}^9
)?
--hints--
reversibleNumbers()
should return 608720
.
assert.strictEqual(reversibleNumbers(), 608720);
--seed--
--seed-contents--
function reversibleNumbers() {
return true;
}
reversibleNumbers();
--solutions--
// solution required