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The first American-made pocket-sized calculator, the Bowmar 901B (popularly termed The Bowmar Brain), measuring 5.2 by 3.0 by 1.5 inches (132 mm × 76 mm × 38 mm), came out in the Autumn of 1971, with four functions and an eight-digit red LED display, for US$240, while in August 1972 the four-function Sinclair Executive became the first ...
The HP-35, introduced on February 1, 1972, was Hewlett-Packard's first pocket calculator and the world's first handheld scientific calculator. [7] Like some of HP's desktop calculators it used RPN. Introduced at US$395, the HP-35 was available from 1972 to 1975.
The 1:4 abacus, which removes the seldom-used second and fifth bead, became popular in the 1940s. Today's Japanese abacus is a 1:4 type, four-bead abacus, introduced from China in the Muromachi era. It adopts the form of the upper deck one bead and the bottom four beads.
An early graphing calculator was designed in 1921 by electrical engineer Edith Clarke. [1] [2] [3] The calculator was used to solve problems with electrical power line transmission. [4] Casio produced the first commercially available graphing calculator in 1985.
Was the first scientific calculator to fly in space in 1973. [5] HP-35 calculators were carried on the Skylab 3 and Skylab 4 flights, between July 1973 and February 1974. [6] Is the first pocket calculator with a numeric range that covered 200 decades (more precise 199, ±10 ±99). [5]
The stepped reckoner was based on a gear mechanism that Leibniz invented and that is now called the Leibniz wheel. It is unclear how many different variants of the calculator were made. Some sources, such as the drawing to the right, show a 12-digit version. [5] This section describes the surviving 16-digit prototype in Hanover. Leibniz wheel
Blaise Pascal and Wilhelm Schickard were the two original inventors of the mechanical calculator in 1642. [1] For Pascal, this was an adding machine that could perform additions and subtractions directly and multiplication and divisions by repetitions, while Schickard's machine, invented several decades earlier, was less functionally efficient ...
Cycles of the unit digit of multiples of integers ending in 1, 3, 7 and 9 (upper row), and 2, 4, 6 and 8 (lower row) on a telephone keypad. Figure 1 is used for multiples of 1, 3, 7, and 9. Figure 2 is used for the multiples of 2, 4, 6, and 8. These patterns can be used to memorize the multiples of any number from 0 to 10, except 5.