Thomas Fantet de Lagny | |
|---|---|
 | |
| Born | 7 November 1660 |
| Died | 11 April 1734 (aged 73) |
| Nationality | French |
| Known for | Calculating π |
| Scientific career | |
| Fields | Mathematics |
| Institutions | French Academy of Sciences |
| Notable students | Adrien Maurice de Noailles |
Thomas Fantet de Lagny (7 November 1660 – 11 April 1734) was a French mathematician, well known for his contributions to computational mathematics, and for calculating π to 112 correct decimal places.