 Cracovian

In astronomical and geodetic calculations, Cracovians are a clerical convenience introduced in the 1930s by Tadeusz Banachiewicz for solving systems of linear equations by hand.Such systems can be written as "Ax" = "b" in matrix notation where "x" and "b" are column vectors and the evaluation of "b" requires the multiplication of the rows of "A" by the vector "x".