The significant 18th century Swiss mathematician Leonhard Euler (1707-83) is noted for solving the 'Seven (What?) of Königsberg problem'?
Contributions of Leonhard Euler to mathematics numbers, which had fascinated mathematicians since Euclid. Euler made progress toward the prime number theorem and conjectured the law of quadratic reciprocity. The two concepts are regarded as the fundamental theorems of number theory, and his ideas paved the way for Carl Friedrich Gauss. In 1736 Euler solved, or rather proved unsolvable, a problem known as the seven bridges of Königsberg. The city of Königsberg, Kingdom of Prussia (now Kaliningrad, Russia) is set on the Pregel River, and included two large islands which were connected to each other and the mainland by seven bridges. The question is whether it is
Contributions of Leonhard Euler to mathematics facilitated the use of differential equations, in particular introducing the Euler–Mascheroni constant: One of Euler's more unusual interests was the application of mathematical ideas in music. In 1739 he wrote the "Tentamen novae theoriae musicae," hoping to eventually integrate music theory as part of mathematics. This part of his work, however did not receive wide attention and was once described as too mathematical for musicians and too musical for mathematicians. The works which Euler published separately are: Contributions of Leonhard Euler to mathematics The 18th-century Swiss mathematician Leonhard Euler (1707–1783) is among the most prolific and successful mathematicians in the