(1) Cranmer Abacus-subtract by 5-learn the rules – YouTube
https://www.youtube.com/watch?v=vVwlltrhTG0
Educational Services for Blind/Low Vision -Specialized Instruction in Technology/Braille/Nemeth and other Blind skills
https://www.youtube.com/watch?v=vVwlltrhTG0
https://www.youtube.com/watch?v=vVwlltrhTG0
https://www.youtube.com/watch?v=KHkMEvHKVgs
https://www.youtube.com/watch?v=MnQmPvEwzFo
https://www.youtube.com/watch?v=OG7gNWzZHhg
https://www.youtube.com/watch?v=WJZv5WG9PJs
https://www.youtube.com/watch?v=NpYWnuGmChM
https://www.youtube.com/watch?v=QGGqCH7fZJc
https://www.youtube.com/watch?v=0oqlpGOSSMc
https://www.youtube.com/watch?v=DVrUVEDZRi4