- (2/-1) Diagrams of sets containing various numbers of sometimes-interlocking circles are named for this mathematician, who called them â€œEulerian circlesâ€ in 1880.
- (4/-2) In 1876, then-Congressman James A. Garfield wrote a new proof of this triangle-related theorem named for a Greek mathematician.
- (6/-3) Two of these rectangular arrays of numbers can be multiplied if the number of rows in the first equals the number of columns in the second.
- (8/-4) A unit of magnetic field density is named for this German mathematician who developed modular arithmetic.
- (10/-5) The main operations in the type of Algebra named for this 19th century mathematician are â€œand,â€ â€œor,â€ and â€œnot.â€

View the BBCode version