# Abacus dating

## How to Use a Chinese Abacus | Sciencing

The accountant sits in the middle of his side of the table, so that everybody can see him, and so that his hand can move freely at its work. In the lowest space on the right, he places the heap of the pence; in the second the shillings; in the third the pounds…As he reckons, he must put out the counters and state the numbers simultaneously, lest there should be a mistake in the number. When the sum demanded of the sheriff has been set out in heaps of counters, the payments made into the Treasury or otherwise are similarly set out in heaps underneath.

The lower line is simply subtracted from the upper. In the Middle Ages, wood became the primary material for manufacturing counting boards; the orientation of the beads also switched from vertical to horizontal. In Western Europe, as arithmetic calculating using written numbers gained in popularity in the latter part of the Middle Ages, the use of counting boards began to diminish and eventually disappear by Arithmetic brought about the invention of logarithms by John Napier and logarithmic scales by Edmund Gunter.

In , William Oughtred used these two inventions together and invented the slide rule which lasted until modern times when the scientific calculator became popular in the early s. The abacus, called Suan-Pan in Chinese, as it appears today, was first chronicled circa C. The device was made of wood with metal re-inforcements.

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In Japanese, the abacus is called Soroban. The design of the schoty is based on a pair of human hands each row has ten beads, corresponding to ten fingers. The abacus is operated by sliding the beads right-to-left. If you hold out both hands in front of you, palms facing out, you will see that your two thumbs are beside each other and two sets of 4 fingers spread out from there. Similarily, on the schoty , each row has two sets of 4 beads of the same colour on the outside, representing the two sets of 4 fingers and the two inner-most beads of the same colour representing the two thumbs.

The "home" position for the beads is on the right hand side.

The bottom-most row represents 1s, the next row up represents 10s, then s, and so on. So, counting is similar to counting on one's fingers, the beads move from right to left: Careful observers will note that the metal rods, on which the beads slide, have a slight curvature to prevent the "counted" beads from accidently sliding back to the home-position.

There have been recent suggestions of a Mesoamerican the Aztec civilization that existed in present day Mexico abacus called the Nepohualtzitzin , circa C.

## Milestone-Proposal talk:The Abacus

Since it was made from perishable materials it is impossible to know whether such a tool ever existed. There is also debate about whether the Incan Khipu was a three-dimensional binary calculator or a form of writing, or both. According to the author, multiplication and division are easier using this modified abacus and square roots and cubic roots of numbers can be calculated.

The abacus is still in use today by shopkeepers in Asia and "Chinatowns" in North America. The abacus is still taught in Asian schools, and a few schools in the West. Blind children are taught to use the abacus where their sighted counterparts would be taught to use paper and pencil to perform calculations. One particular use for the abacus is teaching children simple mathematics and especially multiplication; the abacus is an excellent substitute for rote memorization of multiplication tables, a particularily detestable task for young children.

The abacus is also an excellent tool for teaching other base numbering systems since it easily adapts itself to any base. The abacus, as a portable computing device, continued to evolve into the modern slide-rule, the last mechanical evolution of a portable calculating device before the electronic era brought about digital calculators. In the Hewlett Packard HP scientific calculator made the slide-rule obsolete.

A few decades later scientific calculators evolved into programmable calculators able to display graphs and images on bitmapped LCD screens. In the 21st century, portable counting devices rarely exist as separate entities. Instead they are simulated as Apps running on desktop computers, smartphones and tablets. Civilization, which began recording history with a stylus and a clay tablet thousands of years ago is re-using those original terms today.

The tablet is made of marble x57x5cm and was used by the Babylonians circa B. Photo from the National Museum of Epigraphy, Athens. See endnote for link to video on using a counting board. The Roman hand-abacus was the first portable counting board.

### Additional source for ancient Greek and Roman history of the abacus

It is thought that early Christians brought it to the East. Roman culture could have been introduced to China as early as C.

- The Abacus: A Brief History.
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The Schoty is a Russian abacus invented in the 17 th century and still used today in some parts. Based on the ten fingers of a pair of hands, the numbers on the right indicated the multipliers for the beads in the corresponding row. If you have a gut feeling that you are being lied to about this, ask for his home phone number and see how he responds. Lie 4 - "No one understands me like you do" - This one can be designed to get you to feel sorry for him. You know for certain that this is just massive manipulation when it is closely followed by a large request such as borrowing money or asking to move in with you.

Lie 5 - "I'm not seeing anyone else" - Well, maybe. Pay attention to when and how this information is offered in a relationship. Just like some of the other lies, offering this information too soon or when it is not requested is a huge warning sign that someone is trying to pull the wool over your eyes. One powerful piece of advice offered by coach Bj is to trust your gut instinct. If something is not making sense or adding up, pursue it. Don't try to talk yourself out of it or excuse your intuition away. View my complete profile.