Decimal arithmetic was explained by Simon Stevin in 1585,
but Stevin’s notation, lacking the decimal point, was
cumbersome. The decimal point was introduced by Bartholomaeus
Pitiscus, then adopted and taught by John Napier. The popularity
of logarithms made its use common.
John Napier also invented a calculating aid in 1617 known as
“Napier’s bones.” Only five years later, in
1622, William Oughtred created the first slide rule, an analog
calculator based on logarithmic scales. Blaise Pascal invented the
mechanical calculator, known as the “Pascaline,” in
1645. Charles Babbage’s Difference Engine, in 1822, was a
more complex mechanical calculator, but was controlled by programs
stored on punch cards, like the first computers.
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