To help the PLATO computer-based instruction system user achieve the most efficient storage and manipulation of data, this manual begins with a review of the structure of decimal, binary, and octal number systems, and methods for converting from one system to another. The text describes the four basic operations that PLATO employs to manipulate bits of data (shifting, mask, union, and diff) and how these operations can be used to: (1) store data in an integer variable using shifting and masking; (2) pack and recover information; and (3) store data in a variable using segment. Other methods of bit manipulation are described, and an appendix provides tables of number system conversions and internal keycodes. (EMH)