(1) Cranmer Abacus- Subtract by 9-learn the rules – YouTube
https://www.youtube.com/watch?v=WJZv5WG9PJs
Educational Services for Blind/Low Vision -Specialized Instruction in Technology/Braille/Nemeth and other Blind skills
https://www.youtube.com/watch?v=WJZv5WG9PJs
https://www.youtube.com/watch?v=NpYWnuGmChM
https://www.youtube.com/watch?v=pj-kAgmRNLY
https://www.youtube.com/watch?v=Xe31vCLg8gI
https://www.youtube.com/watch?v=gIlPb33w9HY
https://www.youtube.com/watch?v=X2emrX8fFy0
https://www.youtube.com/watch?v=TfBCn-hQTJc
https://www.youtube.com/watch?v=zicOefubeIc
https://www.youtube.com/watch?v=md0osGVpb6I
https://www.youtube.com/watch?v=5ymxWrUCtEE