Mental Math/Abacus Ep.5 - 10's rules : +9,+8,+7,+6 (中文 sub)
10:10
Abacus Mental Arithmetic Ep.6 - 10's rules : +5,+4,+3,+2,+1 (中文 sub)
6:59
Abacus Mental Arithmetic Ep.4 - Adding and subtracting numbers on the Abacus without rules (中文 sub)
6:17
Japan's ancient secret to better cognitive memory - BBC REEL
7:35
How To Use An Abacus
10:27
Abacus # easy # visualization techniques # initial visualization # most awaited
13:59
Abacus Mental Arithmetic Ep.11 - Combo rules : +9,+8,+7,+6
12:20
Abacus Mental Arithmetic Ep.7 - 10's rules : -9,-8,-7,-6
8:24