This document summarizes key topics in computer arithmetic from William Stallings' Computer Organization and Architecture textbook, including: 1) The Arithmetic Logic Unit (ALU) performs calculations and handles integer and floating point representations. It may include a separate Floating Point Unit. 2) Integer values are represented in binary using two's complement, which allows for easy addition, subtraction and negation operations. 3) Floating point numbers follow the IEEE 754 standard and are represented as a sign bit, mantissa and exponent to allow for a wide range of values between +/- infinity.