(1) Cranmer Abacus- Subtract by 8-learn the rules – YouTube
https://www.youtube.com/watch?v=OG7gNWzZHhg
Educational Services for Blind/Low Vision -Specialized Instruction in Technology/Braille/Nemeth and other Blind skills
https://www.youtube.com/watch?v=OG7gNWzZHhg
https://www.youtube.com/watch?v=WJZv5WG9PJs
https://www.youtube.com/watch?v=NpYWnuGmChM
Source: A bat mitzvah girl debuts a new way for blind Jews to participate in an ancient tradition – The Washington Post
https://www.youtube.com/watch?v=QGGqCH7fZJc
https://www.youtube.com/watch?v=0oqlpGOSSMc
https://www.youtube.com/watch?v=DVrUVEDZRi4
https://www.youtube.com/watch?v=6x4A6Y2Lrps
https://www.youtube.com/watch?v=F917QtOuq3U
https://www.youtube.com/watch?v=gUUQhaRYetc