Final answer:
Blaise Pascal, a prominent French mathematician and inventor, created the first mechanical digital calculator in 1642, which could perform addition and subtraction.
Step-by-step explanation:
In 1642, the Frenchman who built a machine that could add and subtract—and who lent his name to a computer language—was Blaise Pascal. The correct answer to the question is A) Blaise Pascal. Pascal had a remarkable life; he was home-schooled and developed a heightened curiosity for mathematics after his father forbade him from studying the subject, leading him to teach himself geometry.
Despite this, Pascal made significant contributions to mathematics, including the fields of probability theory, number theory, and geometry. He also invented the first mechanical digital calculator and contributed to the understanding of fluid statics, exemplified by Pascal's Principle in hydraulic systems.