We are doing addition and subtraction by making use of the complementary numbers. This will be continued on part 3 of the soroban series. 9:43 reasoning behind the specific order of operation 3:12 addition using complementary numbers w.r.t. 5 4:48 subtraction using complementary numbers w.r.t. 5 6:30 addition using complementary numbers w.r.t. 10 8:09 subtraction using complementary numbers w.r.t. 10 https://www.youtube.com/channel/UCxiWCEdx7aY88bSEUgLOC6A The video is created with Theorem of Beethoven's version of Manim. https://www.youtube.com/channel/UCYO_jab_esuFRV4b17AJtAw Creator of Manim. http://www.jahirulamin.com/ Hand model from Amin's tutorial. Thank you to everyone above who have shared their knowledge and software to the whole world. Background music played on a Casio digital piano.