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Contents
# coding: utf-8
class Integer
# An automorphic number is a number whose square terminates in the number
# itself. That is, k is automorphic if the final digits of k<sup>2</sup> are
# the digits of k.
#
# More generally, an <i>n</i>-automorphic number is one of the form
# <i>nk<sup>2</sup></i> which has its last digits equal to <i>k</i>.
# <i>n</i> may be supplied as an argument to this method; otherwise it
# defaults to 1.
#
# Returns true if the number is automorphic; false otherwise. Aliased to
# Integer#curious?.
#
# 25.automorphic? #=> true
# 9376.automorphic? #=> true
# 600.automorphic? #=> true
#
def automorphic?(n=1)
(n * self ** 2).to_s.end_with? self.to_s
end
alias :curious? :automorphic?
end
Version data entries
36 entries across 36 versions & 1 rubygems