Journal of the Mathematics Council of the Alberta Teachers’ Association
Volume 31 Issue 2, April 1993
18 – 22
Checking Polynomial Arithmetic Casting Out 9’s Reincarnated
Murray L. Lauber
Casting out 9·s is a centuries-old method for checking computations With the introduction of calculators and computers, it has lost most of its value But, as we shall see, it is not a completely antiquated procedure. A generalization of it can be used to check polynomial arithmetic, that is, computations involving adding, subtracting, multiplying and dividing polynomials. In addition, it has some affinities with a type of code currently used in detecting and correcting errors in messages transmitted by computers.
