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| At the same time the money-changers and the abacus appeared. This counting tray is an ancient counting tool. There were small objects on it (e.g.: pebbles). The could count by moving them. | The money-changer had a board into his neck just like a table. There was place for the pebbles on it beside the coins. |
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| The money-changers went around the world. | The structure of the counting tray
followed the craftsmen's state of development.
There were suitable places for the
pebbles. These cavities signed the place-value.
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| The early Roman number writing can be seen on the Roman counting board which was found on Salamis Island. (from IV. c B.C.) | The board was suitable for counting. Above the place-value the following signs can be seen: I, V, L, X,... |
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| More and more new objects were
made which were similar to the money-changers' tables.
The Roman abacus developed and flourished from the IV.c. B.C. to the I.c B.C. |
This tool was made of stone and they might count on it with crops. |
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| The tools for counting changed around the 1st century. | The tool was made of bronze. The decimals could be seen on it. |
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| Gerbert a French monk (he became known as Sylvester II. pope) studied maths. He introduced the number zero (0) | He made the arch coloumn abacus in the 10th century. There are 27 axles, each axle contains 9 balls. |
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| The most well-known abacus is the European one. It flourished up to the XVIII. century. | There are 10 axles in a frame. Every axle contains 10 balls. The axles signed the place-values. |
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| At the Slavics there was a tool. It was the szcsoti. | There were painted balls which helped counting. |
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| In China the name of the tool was suan-pan. (12nd century) | The upper balls signed 5. The others signed 1. The usage of it is similar to the Japanese soroban's. |  |
