 Turing’s original paper is concerned with computable (real) numbers. A (real) number is Turing computable if there exists a Turing machine which computes an arbitrarily precise approximation to that number. All of the algebraic numbers (roots of polynomials with algebraic coefficients) and many transcendental mathematical constants, such as e and \(\pi\) are Turing-computable. Turing gave several examples of classes of numbers computable by Turing machines (see section 10 Examples of large classes of numbers which are computable of Turing 1936–7) as a heuristic argument showing that a wide diversity of classes of numbers can be computed by Turing machines.