A neuropsychological test used in the diagnosis of Alzheimer's disease. The subject gets one of more digits s/he has to cross out from a list of numbers. The resulting score consists of the correctly crossed out numbers minus the incorrectly crossed out numbers.
References Taylor, M.A. (1999). The fundamentals of clinical neuropsychiatry. New York: Oxford University Press. pp. 357–358. ISBN 0-19-513037-5.