After seeing how students multiply multiple digit numbers by the lattice method, I was reminded of Napier’s Bones. John Napier (1550-1617) developed this tool for increasing the speed and accuracy of multiplications. His Napier’s Bones consisted of rectangular rods inside a board, or frame. On each rod, or bone, is written the multiplication of a single digit by 1, 2, 3, 4, 5, 6, 7, 8, and 9. Each number is written within a square divided by a diagonal line. Each tens digit is above the diagonal line and the ones digit is written below the diagonal line. The left side of the board is divided into squares marked with the digit 1 through 9. The squares on the side of the board are the same size as the squares on the bones. In fact, the fifth square on the left side of the board aligns with the fifth square in any bone. And that particular bone’s square has the value for five times the value of the bone. Since I have an interest in Baroque science, I decided to make my own set of bones.
Tomorrow I'll bring pictures and directions. Meanwhile, here is the link where I learned how to use them.