Pierre Rémond (only later to become de Montmort) followed his father's advice and began to study law. However he became bored with this subject and decided to go abroad. He went to England and toured round the country, then going to Germany and again visiting a number of places. By the age of 21 he was back in France where he began to study under Malebranche.
Malebranche taught Pierre philosophy and Descartes's physics. Pierre went on to study the latest mathematics, in particular studying algebra and geometry.
When Pierre returned to France in 1699 he came into a large inheritance from his father. He used this wealth to purchase an estate at Montmort (and therefore became Pierre Rémond de Montmort). He lived most of his life in Château de Montmort on his estate and often invited top mathematicians to visit him. For instance Nicolaus(I) Bernoulli spent three months at Château de Montmort.
Montmort's reputation was made by his book on probability Essay d'analyse sur les jeux de hazard which appeared in 1708. The book, which is a collection of combinatorial problems, is a systematic study of games of chance and shows that there is important mathematics in this area.
Montmort collaborated with Nicolaus(I) Bernoulli and he was also a friend of Taylor. At a time of high feelings in the Newton-Leibniz controversy it says a lot for Montmort that he could be friends with followers of both camps.
In addition to those mentioned above, Montmort corresponded with Craig, Halley, Hermann and Poleni.
Montmort was elected to be a Fellow of the Royal Society in 1715, when he was on a trip to England. The following year he was elected to the Académie Royale des Sciences.