Old Time Calculator

Old Time Calculator

Old Time Calculator

Do you know how to do your multiplication table? Have you ever used an old-fashioned slide rule? Here's a calculator and a slide rule, both using the arc scaled incommensurate. For example, the multiplier of 5 divided by 1 is 5 / 1 = 5.



Before the invention of modern calculators, people would calculate by using various counting devices. Early human beings may have used their fingers and toes for some problems. As the earliest civilizations grew, merchants may have used stones or seeds to help them with equations. The beads of the abacus eventually became vital to the trade of goods and services. Other devices used before calculators include the slide rule, Napier's bones, and early machines like Babbage's analytical engine. (Source:

The way you use an abacus to calculate depends on the style and design of the tool. A standard Chinese abacus has six rods, an upper deck with two beads on each rod, and a lower deck with five beads on each rod. Every rod represents a place value, with hundred thousands on the far left, ten thousands next, thousands, hundreds, tens, and ones on the far right. All beads begin in the lowest position stacked at the bottom of the abacus. You can count numbers by pushing beads into the farthest up position. For example, to count one, you would move one bead on the lower rack on the far right rod all the way up. To add numbers, you would move beads up on the rack that corresponds with the place value of each number. The number of beads in the up position will show the sum. Some people still use the abacus to calculate sums. Blind people often find abaci useful because these tools enable them to manipulate the beads and feel them to find answers to math problems. Teachers may use abaci with young students to help them learn place value and other fundamental math concepts. Architects working in some parts of the world use abaci to measure dimensions and plan designs. Some expert abacus users can manipulate the beads faster than someone entering numbers into a calculator. (Source: www.mortgagecalculator.org)


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