Sha256: fece3ae770380aa44a6b8e9070c16cb9a672ea960b09f431bcf9af95ad556bab
Contents?: true
Size: 545 Bytes
Versions: 19
Compression:
Stored size: 545 Bytes
Contents
# coding: utf-8
class Integer
# A Dudeney number is a positive integer that is a perfect cube such that
# the sum of its decimal digits is the cube root of the number.
#
# Returns true if self is a Dudeney number; false otherwise.
#
# 4913.dudeney? #=> true
# 5832.dudeney? #=> true
# 98.dudeney? #=> false
#
def dudeney?
# The ugly hack below is seemingly needed for 1.8 compatibility. I ave
# yet to understand why.
Math.cbrt(self).to_s.sub(/\.0$/,'') == self.digits.reduce(:+).to_s
end
end
Version data entries
19 entries across 19 versions & 1 rubygems