Who developed a mechanical device in the 17th century that could add, subtract, multiple, divide and find square roots?

The mechanical device developed in the 17th century that could add, subtract, multiply, divide, and find square roots was developed by Blaise Pascal, who is often credited with creating one of the early mechanical calculators, the Pascaline, around 1642. However, the Pascaline primarily performed additions and subtractions.

For a device that could perform a wider array of calculations including multiplication, division, and finding square roots, you might be thinking of the work of Gottfried Wilhelm Leibniz. Leibniz improved upon Pascal’s designs and created the Step Reckoner (or Leibniz Wheel) in the late 17th century, which could perform addition, subtraction, multiplication, division, and had capabilities for calculating square roots through repeated operations.