1. Subtraction on the Cranmer Abacus – Rule of 0 Sara Larkin Math Consultant Iowa Educational Services for the Blind and Visually Impaired Resource Used: Millaway, S. M. (2002). Abacus basic competency: A counting method. American Printing House for the Blind.

2. Rule of 0 Applies whenever you are moving one bead at a time away from the counting bar, and the rod you are counting on has no more beads pushed against the counting bar, but does have a one bead set in the next column to the left. Move the one bead in the next column to the left away from the counting bar with the left index finger Return all 9 beads in the ones column towards the counting bar simultaneously

3. Practice Problems 12 – 9 = 3 73 – 18 = 55 422 – 36 = 386 804 – 487 = 317