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![Standard Soroban (Abacus) / 23 digits [43300]](http://ecx.images-amazon.com/images/I/41vS0O6ycEL.jpg)
Common perception of all over the world
Abacus have long history. Perhaps it s history equal to human s. There are various method and tools to count, but common concept is "more easier to handle number". Interestingly, the method for this purpose is almost same from east to west.
What s Soroban ?
Soroban is a kind of these tools (Abacus). Especially, these in East Asia are called "Soroban". The original Abacus was consisted with ditch on plane and the ball moving on it. The shape and number of balls have been changed for usefulness. For example - there are some scene required to calculate speedy. The number of balls and shape - this is the current standard.
Features of standard
1. Material - Birch ball. Move smoothly, stop firmly. Good material (wood) have this confliction. Birch is most popular. The balls of Abacus grow like your skill. Gradually, the feature of wood become clearly.
2. Digits - 23. This number is most popular. Almost all case, 23 digits is sufficient to handle number. And length fits to bag.
Soroban grow also
Soroban (Abacus) grow like your skill, but need definite time. So, in case you are going to handle for a long time. Good one become good your "own" Soroban. In that sense, this one is standard.
Material : birch ball, ebony frame / 13×0.6×2.5 (inch) / 5.7 (oz) / 1 ball (having a value of five) and 4 balls (having a value of one)
