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Abacus Calculator for iPad

Buy Abacus Calculator for iPad at iTunes Store

• Chinese abacus calculator for counting arithmetic.
• Now you can exercise your arithmetic with this virtual abacus as one of the most ancient calculators invented by the Chinese.
• Great tool for education to teach kids how to you carry digit for arithmetic.
• The Chinese abacus has the advantage over Japanese abacus because it uses the carry digit explicitly for arithmetic.
• The Chinese abacus has both carry 5 and carry 10 digit, making it one of the most ingenious and intuitive ways to do arithmetic.

Features:

• 24 rainbow bead colors to choose from
• 12 rainbow frame colors to choose from
• Matt or shiny bead texture to choose from
• All-in-one 1-click design
• Easy to use, just swipe beads
• Addition and subtraction arithmetic
• 8-digit precision
• Decimal system
• Can be used as counting beads for kids
• Carry 5 and carry 10 digit for arithmetic.

Chinese abacus basics, representation of decimal numbers:

Columns of beads:

• Each column of beads represents a decimal digit.
• Right column represents 1's, i.e., 1 - 9, the least significant digit.
• The second right column represents 10's, i.e., 10 - 90, the next significant digit.
• The third right column represents 100's, i.e., 100 - 900, etc.

Rows of beads:

• The 2 beads in the top rowrepresent digit 5 or 10.
• The 5 beads in the ottom row represent digit 1, 2, 3, 4 or 5.

Position of beads:

• Moving one bottom bead up adds 1.
• Moving one top bead down adds 5.
• The digits represented by the beads centered on the middle horizonal bar is the number it adds up.
• Zero is represented by no beads next to the middle horizontal bar, i.e., all top beads up, and bottom beads down.

How to calculate using the abacus:

• Arithmetic calculation starts from right to left digit columns.
• In adding,
  • top beads move down while bottom beads move up.
• In subtraction,
  • top beads move up while bottom beads move down.
• E.g.:
  • Move 3 bottom beads up = 1 + 1 + 1 = 3.
  • Move 1 top bead down = 5.
  • Move 1 top bead down + 3 bottom beads up = 5 + (1 + 1 + 1) = 8.

Using carry digit in addition arithmetic:

• Carrying Carry-5 digit over:
• If 5 bottom beads moved up, it is carried over to the top row,
  • i.e., 1 + 1 + 1 + 1 + 1 = 5.
  • i.e., 5 bottom beads are equivalent to 1 top bead.
    • At this point, a top row bead will move down to represent 5,
    • then restore the original 5 bottom row beads by moving down too
    • (because 5 is already represented by the top row bead as the "carry" over, so the bottom beads have to be subtracted in order not to double-count the 5 in the carry over).
• Carrying Carry-10 digit over:
• When the top 2 beads are moved down,
  • i.e., 5 + 5 = 10,
    • it will carry over to the next digit (next left column).
    • So you add one bead to the adjacent left bottom row,
    • and restore the original 2 top beads back up
    • (because it is already carried over by the left digit, you need to subtract it so you won't double-count the 10).

Using carry digit in subtraction arithmetic:

• If there are not enough beads to subtract in a column, borrow the carry digit.
• Borrowing carry-10 digit, e.g..:
  • 7 = 10 - 3, so you subtract 10 and add 3.
  • i.e., you remove one bead from the next-left column, and add 3 beads to the current column.
• Borrowing carry-5 digit, e.g.:
  • 2 = 5 - 3, so you subtract 5 and add 3 in the same column,
  • i.e., you remove one bead from top row, and add 3 beads to the bottom row.

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