When calculator was invented?
The modern electronic calculator as we know it came onto the market just before the 1960s (1957), it was made in Japan under the company name, Casio, which is still a large manufacturer of calculators today.
Well the modern calculator with circuits was invented by William Seward Burroughs, while the first calculator (slide and rule) was invented by W. Oughtred (1574-1660). Nobody "discovered" the calculator in the contemporary sense. It was a natural outgrowth of continuous integrated circuit miniaturization.
The oldest calculator, the abacus, was invented in ancient Egypt(unknown date). The first Mechanical calculator, known as the Calculating clock, was invented by Willhelm Schickard in 1623. The first electronic desktop calculator were announced by the Bell Punch Co, in Uxbridge England in 1961. Finally, the first handheld computer was invented in 1980.