The abacus is a simple calculating machine that is used for doing arithmetic. A modern abacus is made of beads, rods, and a frame. The rods are fastened in the frame, and each stand for a place in the decimal system. One rod stans for units, one for 10’s, one for 100’s, and so on. The beads are counters. Numbers are added or subtracted by moving the beads on the rods.
Why the abacus was invented
The abacus wa invented thousands of years ago. It offered a way of doing arithmetic with using written numerals. And it was used in many ancient civilization.
The numeral of ancient times were very awkward for doing arithmetic. The trouble was that they did not express zero of place value.
The numeral of ancient times were very awkward for doing arithmetic. The trouble was that they did not express zero of place value.
For example, compare our numerals with the roman ones. Our numeral 5 can stand for 5, 50, or 500, depending on the place it is given. In the number 555 each 5 has a different value. The romans used letters as numerals and expressed place by using a different letter. 5, 50, and 500 were written as V, L, and D. Without the idea of zero and place, there was no way that the same nuimerals could be made so stand for more than one number. That is, V could not be made to stand for any number accept 5.
This system of numerals made written arithmetic very difficult. So the romans, like other ancient peoples, used the abacus. The idea of place was built into the abacus. One counter could be made to express 1, 10, or 100, according to its place on the abacus.
Thw abacus offered a quick and easy way of adding and subtracting. It could also be used for multiplication and division. Multiplication was done by adding equals groups. Division was done by substracting equal groups.
This system of numerals made written arithmetic very difficult. So the romans, like other ancient peoples, used the abacus. The idea of place was built into the abacus. One counter could be made to express 1, 10, or 100, according to its place on the abacus.
Thw abacus offered a quick and easy way of adding and subtracting. It could also be used for multiplication and division. Multiplication was done by adding equals groups. Division was done by substracting equal groups.
How to make and use abacus
The abacus is still widely used today. For example, it is used in china and japan. There numerals do not express place. People who are used to the abacus can do arithmetic on it very quicly. A Japanese abacus can be bought in almost any toy store or five-and-ten. The intruction that come with it explain how it works.
However, it is very simple to make an abacus like those of ancient times. You can draw four lines in sand, dust, or soil and use pebbles as counters. Or yopu can rule heavy lines on apiece of paper or cardboard. Use buttons, bottlecaps. Dried beans, or pebbles as counters.
The lines, from right to left, stand for 1’s (or units), 10’s, and 1,000’s. For example. If you want to express 2,222, you put two counters in each row. If you want to express 2,220, you put two counters in three of rows and none in the units row. Make up some numbers of your own and express them.
Now suppose you want to add 271 and 302. Set up one of the numbers; then set up the second number. A glance at the abacus give you the sum.
This is how to subtract 271 from 394. Set up the large number on the abacus and take away the counters that represent thw smaller number.
However, it is very simple to make an abacus like those of ancient times. You can draw four lines in sand, dust, or soil and use pebbles as counters. Or yopu can rule heavy lines on apiece of paper or cardboard. Use buttons, bottlecaps. Dried beans, or pebbles as counters.
The lines, from right to left, stand for 1’s (or units), 10’s, and 1,000’s. For example. If you want to express 2,222, you put two counters in each row. If you want to express 2,220, you put two counters in three of rows and none in the units row. Make up some numbers of your own and express them.
Now suppose you want to add 271 and 302. Set up one of the numbers; then set up the second number. A glance at the abacus give you the sum.
This is how to subtract 271 from 394. Set up the large number on the abacus and take away the counters that represent thw smaller number.
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