class Fixnum
	def closest_fibonacci
		if self < 0
			return "Provide a positive integer or 0"
		end
		fibNum = 0
		if self == 0 || self == 1 || self == 2 || self == 3
			fibNum = self
		else
			n1 = 2
			n2 = 3
			while fibNum < self
				fibNum = n1 + n2
				n1 = n2
				n2 = fibNum
			end
			fibNum = n1
		end
		return fibNum
	end
end
