Office Pro Calculators dual power black number buttons header type


Azoosh presents the following easy to use free online calculators for calculations of percentage difference, the lease number of months based on your loan amount (+ residual value & interest rate), your ideal weight based on your height (for male & female), and pregnancy conception date and due date.


Calculators have been used to perform calculations since ancient times


2700 ~ 2300 BC : The Abacus made its first known appearance in Mesopotamia, where it was used by the Sumerians. The abacus usually consists of movable beads representing digits on a number of rows.

1617 : Napier’s Bones (aka Rabdology) a manually-operated calculating device was invented by John Napier, in Scotland. It was used for calculation of products and quotients of numbers, and based on Arabian lattice multiplication.

1620 ~ : The Slide Rule, a logarithmic rule for multiplication and division using dividers was invented by William Gunter. The slide rule was based upon Napier’s Bones, and was used for centuries until mechanical and electronic calculators were invented.

1623 : The Calculating Clock, aka the first mechanical calculator was invented by Willhelm Schickard, a German professor. It used a version of Napier’s bones for multiplication with a mechanical adding and subtracting calculator using gears.  carry.

1642 : Pascal’s Calculator aka The Pascaline, a mechanical calculator capable of multiplication, division, addition, and subtraction was invented by Blaise Pascal, in France.

1673 : The Stepped Reckoner aka Leibniz Wheel or Stepped Drum, a digital mechanical calculator was invented by Gottfried Leibniz, in Germany.

1709 : The pinwheel calculator was first built by Giovanni Poleni, and made of wood.

1820 : The Arithmomete calculator was invented by Charles Xavier Thomas’s, in France. It was the first digital mechanical calculator that was strong and reliable enough to be used in an office environment everyday. It could add and subtract two numbers directly and perform long multiplications and divisions effectively by using a movable accumulator for the result.

1834 : The direct multiplication machine was invented by Luigi Torchi.

1851 : The Schilt key-driven adding machine invented by Victor Schilt was exhibited at the Crystal Palace Exposition in London.

1853 : The Scheutz Difference Engine, the world’s first printing calculator was completed.

1874 : The Pin-Wheel Calculator was developed further by Frank Baldwin. W.T. Odhner in Sweden independently developed pin-wheel calculators.

1878 : The Direct Multiplication Machine was built by Raymond Verea.

1884 : The Comptometer, a key-driven adding and calculating machine was invented by Dorr E. Felt.

1885 : William Seward Burroughs filed his first patent for a recording adding machine.

 1957 : The Casio Model 14-A calculator, the world’s first all-electric relatively compact calculator was released by the Casio Computer Company, in Japan. It was based on relay technology (no electronic logic), and was built into a desk.

1961 : Electronic Desktop Calculators were first announced, by the Bell Punch Co., in England, with the Anita Mk VII and Anita Mk 8. These models used vacuum tubes with numerical display.

1963 : Transistorised Desktop Calculators were first made commercial. The models available included the Friden EC130 & EC132, Mathatron, IME 84, and Sharp CS10A, and cost as much as a family sized car.

1965 : The Cal-Tech, the first hand-held electronic calculators project was started by Texas Instruments.

1965 : The Olivetti Programma 101 was introduced.

1967 : The Monroe Epic programmable calculator became available on the market.

1969 : The first battery powered hand-held electronic calculators were introduced, including the first calculator using just LSI chips (Large Scale Integration) – Sharp QT-8D with ICs by Rockwell, and green fluorescent tube displays.

1970 : The first pocket sized electronic calculators were released, including Canon Pocketronic, Sanyo ICC-0081, Sharp EL-8, and Busicom LE-120A. | The first use of “calculator on a chip” was introduced by Mostek of Dallas on the Busicom Junior desk calculator. | LED (Light Emitting Diode) were first used on displays, in the Busicom LE-120A.

1971 : The Intel 4004, the first calculator to use a microprocessor.

1972 : The first scientific pocket calculator was introduced by Hewlet-Packard, with the HP35. The ultra-thin Sinclair Executive was launched. LCD (Liquid Crystal Device) displays briefly appeared on the Lloyds Accumatic 100 Lloyds, and Rapidman 1208LC. | The first use of C-MOS (Complementary Metal-oxide Semiconductor) integrated circuits in a calculator, with the Sharp EL-801.

1973 : The first Sharp “COS” (Crystal on Substrate) reflective LCD calculators, which included the Sharp EL-805S.

1974 : A patent for the miniature electronic calculator was awarded to Texas Instruments, based on the CalTech in 1965. | The first hand-held programmable calculator was released by Hewlett Packard, with the HP65.

1975 : The Casio pocket-LC became the first calculator to use black numbers, using TN (Twisted Nematic) LCD (Liquid Crystal Display).

1976 : The first calculators with solar cells, to charge internal batteries, were released. Models included the Sun Man Sharp EL-8026 and the Royal Solar I / Triumph-Adler 1980.

1978 : The first solar powered calculators, one of which was the Teal Photon. | The first credit card sized calculators was released, the Casio Mini Card LC-78d LC-78.

1980 : The first hand-held computer calculator, the Sharp PC1211 / Tandy TRS80 PC-1 was released, with a QWERTY keypad, running the BASIC language.

CASiO Calculators continued from the part 1 video (see above) : part 2 : Building Quality : Part 2 shows the methods of comprehensive research, rigorous testing, which result in a wide range of powerful calculators from simple devices to the advanced scientific and graphing calculators. (Casio Japan video uploaded in 2017)


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The History of the Abacus

The abacus also known as a counting frame, was first used in the ancient Near East, China, Russia, and Europe, as a calculating tool centuries before the adoption of the written Hindu-Arabic numeral system. It is unsure where the origin of the abacus was exactly. Originally the abacus used moving beans or stones in grooves of sand or on tablets of wood, metal, or stone. The modern day abacuses are constructed with a bamboo frame with beads sliding on wires, and still remain in common use in parts of Eastern Europe, Russia, Japan, China and Africa, by merchants, traders, clerks, visually impaired people, and for teaching arithmetic to children.

The video below shows how to use the open-end abacus, and also explains the history and principles of the decimal number system. It also shows how to do grouping in addition, regrouping in subtraction and comparison of number values.

How To Use An Abacus

Eddy explains how to use an abacus to add, subtract, multiply and divide (this video provided by Ignite Spot Accounting Services has had over 383,000 views since June 2016)

The tutorial video below by The HEV Project is an Abacus lesson which includes an introduction, and shows the proper technique to use. (this video has had over 1.5 million views since July 2013)

How to use a classic Chinese abacus

The video tutorial shows how to do the basic functions on a classic Chines abacus (this video provided by Pelle Lindblå has had over 410,000 views since April 2013)

Free online abacus to use ~


Music Calculators

The portable Music Function Electronic Desktop Calculator from Amazon can play piano, and also features Chinese Mandarin language, voice reading, 12-Digits LCD display calculator launchpad with alarm clock.

Watch a music calculator used for the first time by Amosdoll Music (video uploaded in 2019 ~ over 40,000 views)

Listen to songs played on the music calculator by Amosdoll Music (video uploaded in 2019 ~ over 540,000 views)


How to Make Words on a Calculator

Words you can make with your calculator by typing certain numbers, and then turning the calculator upside down

Top 10 Calculator words (video uploaded by Edepot in 2014)

YouGart shows you words you can form with a calculator upside down (video 1)

& more words you can form with a calculator upside down (video 2)…


Free online calculators provide over 200 free online calculators to help you calculate math, finance, fitness, health, and more. The financial calculators include mortgages, loans, interest, retirement, investment, inflation, income tax, compound interest, sales tax and more. The fitness & health calculators include BMi, calories, body fat, pregnancy and more. The math calculators include scientific, fraction, percentage, random number generators and more. The other calculators include age, date, time, hours, conversions, concrete, password generation and more.

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_________________________ provide many free online calculators in many areas such as savings, loans, debt, budget, automotive, credit cards, investing, mortgage, math, retirement, business, and health.

The website is ranked 59,695 of over 1 billion websites in the World, as of the 22nd October 2020


This page was first uploaded on the 15th October 2019 & last updated on the 22nd October 2020

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