Leonhard Euler
Leonhard Euler (pronounced Oiler) (April 15, 1707 – September 7, 1783) was a Swiss mathematician and physicist. He spent most of his life in Russia and Germany.
Euler made important discoveries in fields like calculus and topology. He also made many of the words used in math today. He came up with the idea of a mathematical function. He is also known for his works in mechanics, optics, and astronomy.
Euler is considered to be the most important mathematician of the 18th century, one of the greatest mathematicians of all time, and also one of the mathematicians who wrote the most. His collected works fill 60–80 volumes. Another mathematician, PierreSimon Laplace said, "Read Euler, read Euler, he is a master for us all".
Euler was featured on the sixth series of the Swiss 10franc bill and on numerous Swiss, German, and Russian postage stamps. The asteroid 2002 Euler was named in his honor. He is also celebrated by the Lutheran Church on their Calendar of Saints on May 24.
Early years
Euler was born in Basel to Paul Euler. He was a pastor of the Reformed Church. His mother was Marguerite Brucker, a pastor's daughter. He had two younger sisters named AnnaMaria and Maria Magdalena. Soon after the birth of Leonhard, the Eulers moved from Basel to the town of Riehen, where Euler spent most of his childhood. Euler's started school in Basel, where he was sent to live with his grandmother. At the age of thirteen he went to the University of Basel. In 1723, he received his Master of Philosophy. At this time, he was receiving Saturday afternoon lessons from Johann Bernoulli, who quickly discovered his new pupil's incredible talent for mathematics.
Images

1957 Soviet Union stamp commemorating the 250th birthday of Euler. The text says: 250 years from the birth of the great mathematician, academician Leonhard Euler.

1753 portrait of Euler by Emanuel Handmann which indicates problems with Euler's right eyelid, possibly strabismus. Euler's left eye, which here appears healthy, was later affected by a cataract.

Map of Königsberg in Euler's time showing the actual layout of the seven bridges, highlighting the river Pregel and the bridges.