Kaprekar numbers: Difference between revisions
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{{task}}
In this task, generate andshow all Kaprekar numbers less than 10,000. For extra credit, count (and report the count of) how many Kaprekar numbers are less than 1,000,000.
A positive integer is a [[wp:Kaprekar number|Kaprekar number]] if it is 1, or if the string representation of its square can be split once into parts consisting of positive integers that when summed add up to the original number.▼
▲A positive integer is a [[wp:Kaprekar number|Kaprekar number]] if it is 1, or if the string representation of its square
For example 2223 is a Kaprekar number as 2223*2223 == 4941729 and 494 + 1729 == 2223▼
;Example Kaprecar numbers:
The series of Kaprekar numbers begins: [[oeis:A006886|1, 9, 45, 55, ...]].▼
▲
▲* The series of Kaprekar numbers begins: [[oeis:A006886|1, 9, 45, 55, ...]].
;Example process:
* The first split is [1, 0000], which is not OK because "a split of all zeroes is not counted; zero is not considered positive".
* Slight optimization opportunity: When splitting from left to right, once the right part consists of all zeroes, no further testing is needed; all further splits would also be invalid.
;Reference:
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;Note
In comparing splits of the square, a split of all zeroes is not counted
▲Example: 10000 (100<sup>2</sup>) splitting from left to right:
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