In mathematics, the supernatural numbers, sometimes called generalized natural numbers or Steinitz numbers, are a generalization of the natural numbers. They were used by Ernst Steinitz in 1910 as a part of his work on field theory. A supernatural number is a formal product: There is no natural way to add supernatural numbers, but they can be multiplied, with . Similarly, the notion of divisibility extends to the supernaturals with if for all . The notion of the least common multiple and greatest common divisor can also be generalized for supernatural numbers, by defining