CALC.EXE is a general purpose calculator, using reverse Polish logic, that works with five basic data types: real numbers, complex numbers, fractions, integers (with binary logic, base b=2, b=8, b=10, or b=16), and polynomials. The real numbers have between 19 and 20 significant digits. Real number functions include, in addition to the usual functions, factorials, permutations, combinations, prime factorizations of integers, greatest common factor, least common multiple, and the group order of one integer modulo another. The complex number functions include also complex values for nth roots, complex powers, etc. In fraction mode you can perform basic operations on fractions which may be displayed in both improper and mixed number form. There are special functions for working with both simple and general continued fractions. In the integer mode you can specify the word size in terms of the number of bits per integer. In addition to normal arithmetic, there are logical operators. The polynomial mode operators include +,-,* and /. Polynomial division yields both quotient and remainder polynomials. Any polynomial with integer coefficients can be completely factored using exact rational linear factors. Polynomials may be up to degree 25 and are easily entered, edited, and evaluated. Other special functions include the ability to determine the fixed and periodic parts of any repeating decimal that represents any fraction. In addition to base 10, repeating decimals may be analyzed and displayed with respect to binary, octal, and hexadecimal formats. Another special function converts any decimal to a simple continued fraction and displays all the convergent terms as fractions and decimals. There is a tutorial file, CALC.TXT, for first-time users.