Dan Terry, age 13, of Rutland, Vt., for his question:
WHAT MAKES A CALCULATOR PERFORM?
A calculator is a device that adds, subtracts, multiplies and divides with accuracy and speed. Miniature electronic circuits make the calculator perform calculations automatically.
Besides adding, subtracting, multiplying and dividing, many of the electronic computers perform more complicated functions, such as extracting square roots and cube roots. Some models have a memory, a device that stores for future use numbers or instructions for solving certain problems.
Manufacturers produce both large, desk top electronic calculators and pocket sized models. The pocket sized model, or minicalculator, has become popular with the general public because it is so convenient to use. This calculator is not only portable, but it can also do all the calculations for such tasks as schoolwork and balancing checkbooks.
Some electronic calculators can solve advanced engineering and scientific problems.
Electronic calculators have different output equipment to record and present information. Some models show answers instantly in a small display window or on a dial. Most minicalculators are of this type.
Other models provide tapes that show the numbers involved in problems and the results. The tapes allow an operator to check if the problems were correctly fed into the calculator. They also provide a permanent record of the results. Most of these calculators are desk top models. Some provide both a display and a tape output.
One type of electronic calculator can handle complicated, multistep tasks similar to those done by small computers. Such a calculator is called a programmable calculator. It carries out difficult tasks by using numbers and programs. Programs are sets of instructions that tell the calculator what jobs to perform with the numbers. An operator feeds the numbers and programs into the calculator by means of a keyboard or other device.
Most of the programmable calculators have several memories in which such data can be stored for repeated use. Programmable calculators are available in both desk top and pocket sized models and have either a display or tape output.
Mechanical calculators are no longer produced, but some offices still use them. They perform basic mechanical operations by means of gears or toothed wheels. Mechanical calculators were widely used before the development of electronic models.
Early devices used by man to aid in calculation included the abacus, which is still used in the Orient.
Blaise Pascal in 1642 deveised what was probably the first simple adding machine using geared wheels. And an improved mechanism for performing multiplication was invented in 1672 by G.W. von Leibniz.