The abacus is the earliest counting device. It is made with rods, stones, and beads Abacus is used for calculation.
Husnain: The abacus was the earliest counting device. That was made using beads, stones on wires or bones. It's used for mathematical calculations.
The Napier's Bones was made in the Scotland 17th century, and John Napier invented this device and used it for Multiplication and Division.
Husnain: John Napier invented Napier's Bones in Scotland 17th Century. It's only used for Multiplication and Division. Napier's Bones is the first decimal-calculating device.
Pascaline's concept started in 1642. Blase Pascal invented this machine. Blase Pascal is a French mathematician, and his father, Étienne Pascal, worked in a tax company, so he had a lot of calculations, so Blase Pascal made Pascaline.
Husnain: Blase Pascal's Father works in a tax company. He needs to make a lot of calculations every day. For this problem, Pascal invented Pascaline, the world's first mechanical device, in 1642. He starts to sell it, but people reject it. Pascal is a French mathematician and Physicist.
Gottfried Wilhelm Leibniz invented this in 1673. He is a German mathematician and Stepped Reckoner or Leibniz Wheel, made in German, and is a calculation & mechanical device.
Husnain: Stepped Reckoner or Leibniz Wheel was invented by German mathematician Wilhelm Leibniz in 1673. It's improved Pascal's invention. It can do Addition, Subtraction, Multiplication, and Division. It's a Mechanical Device using grooved wheels.