# Abacus Calculator

4.7 ( 7357 ratings )
Nástroje Vzdělávání
Vývojář: IntelligeSoft.com
0.99 USD

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.

Features:
• 24 rainbow bead colors (12 shiny bead colors and 12 matt bead colors) for iPad
• 12 shiny bead colors for iPhone
• 12 rainbow frame colors for iPad
• Matt or shiny bead texture for iPad
• Addition and subtraction arithmetic
• 8-digit precision
• Decimal system
• Great educational tool to teach arithmetic as counting beads for kids too
• Chinese abacus version has the advantage of the carry digit for carrying-over arithmetic compared to the Japanese abacus version.

How to calculate using the abacus:
• Each column of beads represents a decimal digit.
• Arithmetic calculation starts from right to left digits.
• The 2 beads in top rows represent digits 5 and 10.
• The 5 beads in bottom rows represent digits 1, 2, 3, 4 and 5.
• For addition, top-beads move down while bottom-beads move up.
• For subtraction, top-beads move up while bottom-beads move down.
• Numbers are represented by the beads centered between the horizontal middle bar.
• 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.
• If 5 bottom-beads moved up, it is carried-over to the top-row, i.e., 1 + 1 + 1 + 1 + 1 = 5. At this point, move one top-row bead down to represent 5 (carry-over) while restore the original 5 bottom-row beads by moving them down (because 5 is already represented by the top row bead as the "carry" digit, you need to subtract 5 from the bottom beads so you wont double-count the 5).
• Similarly, 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-column, and restore the original 2 top-beads back up (because it is already carried over by the left digit, you need to subtract the original beads so you wont double-count the 10).