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The Curta was conceived by Curt Herzstark in the 1930s in Vienna, Austria.By 1938, he had filed a key patent, covering his complemented stepped drum. [3] [4] This single drum replaced the multiple drums, typically around 10 or so, of contemporary calculators, and it enabled not only addition, but subtraction through nines complement math, essentially subtracting by adding.
The machine performs multiplication by repeated addition, and division by repeated subtraction. The basic operation performed is to add (or subtract) the operand number to the accumulator register, as many times as desired (to subtract, the operating crank is turned in the opposite direction). The number of additions (or subtractions) is ...
Mechanical calculator from 1914 An Addiator can be used for addition and subtraction. Two different classes of mechanisms had become established by this time, reciprocating and rotary. The former type of mechanism was operated typically by a limited-travel hand crank; some internal detailed operations took place on the pull, and others on the ...
He designed the machine to add and subtract two numbers directly and to perform multiplication and division through repeated addition or subtraction. Pascal's calculator was especially successful in the design of its carry mechanism, which adds 1 to 9 on one dial, and carries 1 to the next dial when the first dial changes from 9 to 0. His ...
The Comptometer was the first commercially successful key-driven mechanical calculator, patented in the United States by Dorr Felt in 1887.. A key-driven calculator is extremely fast because each key adds or subtracts its value to the accumulator as soon as it is pressed and a skilled operator can enter all of the digits of a number simultaneously, using as many fingers as required, making ...
A slide calculator, also known as an Addiator after the best-known brand, is a mechanical calculator capable of addition and subtraction, once made by Addiator Gesellschaft of Berlin, Germany. Variants of it were manufactured from 1920 until 1982. The devices were made obsolete by the electronic calculator.
"People really didn't know about it until the end of last year," Miller said. "It was out there, but no one really knew much about it." Many of the state's small business owners still don't know ...
Since there are 366 days in each leap year, this needs to be accounted for by adding another day to the day of the week offset value. This is accomplished by adding ⌊ ⌋ to the offset. This term is calculated as an integer result. Any remainder is discarded.