Description This workbook, along with the separately-sold "Answer Guide," will introduce you to all the basic arithmetic facts using The Human Calculator Matrix. Discover all the patterns that will make you feel like a mathlete and a human calculator. The Turn on The Human Calculator in You Answer Guide is available at the link on this page. You will need 10 colored pencils for these exercises. Suggested colors are black, red, blue, pink, green, orange, violet, yellow, brown, and gray.