Learn to calculate using Abacus or Soroban. Sorobacus will help you to learn these ancient calculators with a simple user interface.
SPECIFICATIONS:
Sorobacus supports a minimum of 9 columns (Compact Mode) and a maximum of 13 columns(Normal mode).
Abacus: 2 Heaven and 5 Earth beads. Value is base 16.
Soroban: 1 Heaven and 4 Earth beads. Value is base 10. Indicator on every third column.
Value display can be turned on (for beginners) or off (for experts).
Value can be displayed in decimal or hexadecimal.
Check out Sorobacus and Sorobacus HD (for iPad) at http://www.sorobacus.com.