In 1640, Pascal published an essay on conic sections, and during the next few years, he invented and built a mechanical calculating machine, which was called a Pascaline. When he became twenty-one, Pascal gained interest in Torricelli's work on atmospheric pressure, which led him to study hydrostatics.

In 1650, Pascal took an abrupt hiatus from his research to pursue religion. He joined the Jansenist monastery at Port-Royal in 1654 after he had a religious experience that changed his life. He broke away from the Jansenists in 1658 and returned once again to his studies in mathematics. He worked primarily on calculus and on probability theory with Pierre de Fermat up until his death at the age of 39.