More On Finger Multiplication
Last night, I received the following response to my previous blog entry, Finger Multiplication, the Lattice Method, and At-Risk Students: Dear Jerry, I cannot find en e-mail address to Michael Paul Goldenberg, but I would like to share the following with him in response to his mail via you. In the 1980s I was approached by a mathematics teacher who taught adults early mathematics. In his class he had a group of gypsies and they had taught him how they multiply numbers between 5 and 9 with the fingers. The teacher could not figure out why it worked and wanted me to explain it, so I did. Later I gave this task to my secondary students to solve, and I see it as a good modeling task and exercise in use of algebra for them. I have published the task in a book in 1989 called The Challenge - Problems and Mind-Nuts in Mathematics (in Swedish) and attach here the one page of that book translated into English of the task I call Handy multiplication (fingerfärdig matematik in Swedish). This see