A program designed to plot three-dimensional graphs is described and presented. The program allows the user to select maximum and minimum ranges for X, Y, and Z, and can enlarge a graph on the screen or look at a portion away from the origin. It is in Applesoft BASIC. (MP)

Describes a program written in BASIC, called BIGNUM, that was designed to aid in handling big numbers. The program adds, subtracts, multiplies, divides, and raises to a power integers of up to 1024 decimal digits and is thought to be usable on many types of machines. (MP)

Several BASIC computer programs designed to illustrate concepts in probability are presented. The programs are geared for the Apple II computer, but most samples are adaptable to other systems. (MP)

There are many uses for the shortest path algorithm presented which are limited only by our ability to recognize when a problem may be converted into the shortest path in a graph representation. (Author/TG)

Two kinds of secret writing, codes and ciphers, are discussed. The weakness of a ciphering system mentioned in the March 1981 issue is pointed out, and an alternate method is presented. Programs written in BASIC are presented which can be used to encipher messages and help break ciphers. (MP)

Five problems on the generation and study of prime and related numbers are discussed. Solutions to the problems posed will be in next month's presentation. (MP)

Problems are presented that can be solved with a microcomputer which explore the binary, decimal, and hexadecimal number systems and related problems. (Author/TG)