Sha256: cc2c7ed16f6942e2b63483e1e075a6edc573ea68bc8045155c048cb8a5963046
Contents?: true
Size: 398 Bytes
Versions: 36
Compression:
Stored size: 398 Bytes
Contents
# coding: utf-8
class Integer
def self?
# Formula from: Kaprekar, D. R. The Mathematics of New Self-Numbers
# Devaiali (1963): 19 - 20
dr_star = digital_root.odd? ? (digital_root + 9) / 2 : digital_root / 2
0.upto(digits.size).none? do |i|
(self - dr_star - 9 * i) + (self - dr_star - 9 * i).sod == self
end
end
alias :colombian? :self?
alias :devlai? :self?
end
Version data entries
36 entries across 36 versions & 1 rubygems