What is "prosthaphaeresis"

n. 1 A method of computing by means of a table of natural trigonometrical functions, without multiplication. 2 A reduction to bring the apparent place of a moving point or planet to the mean place.

Prosthaphaeresis was an algorithm used in the late 16th century and early 17th century for approximate multiplication and division using formulas from trigonometry. For the 25 years preceding the invention of the logarithm in 1614, it was the only known generally applicable way of approximating products quickly. Its name comes from the Greek prosthesis and aphaeresis, meaning addition and subtraction, two steps in the process.