Student errors are springboards for analyzing, reasoning, and justifying. The mathematics education community recognizes the value of student errors, noting that "mistakes are seen not as dead ends but rather as potential avenues for learning." To induce specific errors and help students learn, choose tasks that might produce mistakes.…

Several schemes use modular arithmetic to append a check digit to product identification numbers for error detection. Some schemes are discussed, including ones for money orders and library books. Then a foolproof method is presented. (MNS)

Describes mathematical problems which occur when using the computer as a calculator. Considers errors in BASIC calculation and the order of mathematical operations. Identifies errors in spreadsheet and calculator programs. Comments on sorting programs and provides a source for Mathemagical Black Holes. (MVL)