In the beginning of the 19th century the mechanical calculator was developed to perform all sorts of mathematical calculations.
Up to the 1960s it was widely used. Later the rotating part of the mechanical calculator was replaced by an electric motor.
So it was called the electrical calculator.
What is Modern Electronic calculator ?
The electronic calculator used in 1960s was run with electron tubes, which was quite bulky. Later it was replaced with transistors and as a result the size of calculators became too small.
The modern electronic calculator can compute all kinds of mathematical computations and mathematical functions.
It can also be used to store some data permanently. Some calculators have in-built programs to perform some complicated calculations.
