class Integer
def prime?
def prime? return self >= 2 if self <= 3 return false if self % 2 == 0 or self % 3 == 0 (5..(self**0.5).floor).step(6).each do |i| if self % i == 0 || self % (i + 2) == 0 return false end end true end
def prime? return self >= 2 if self <= 3 return false if self % 2 == 0 or self % 3 == 0 (5..(self**0.5).floor).step(6).each do |i| if self % i == 0 || self % (i + 2) == 0 return false end end true end