Concept:The first mechanical calculator was an adding machine designed to perform arithmetic operations automatically.
Explanation:Blaise Pascal, a French mathematician and philosopher, built the first working calculator in 1642.
His device was called the Pascaline, or Arithmetic Machine.
It could add and subtract numbers using a series of gears and wheels.
Unlike previous counting tools, the Pascaline was produced in quantity and actually used for practical calculations.
The other options do not match: Charles Babbage designed the Analytical Engine, a later computer concept; John Napier invented logarithms; Marie Jacquad is not associated with the first calculator.
Therefore, the credit for building the first calculator goes to Blaise Pascal.
Answer:C. Blaise Pascal