A gifted student, Euler published his first memoir at the age of 18. Despite his lack of experience, he tackled complex problems to which he found original solutions. When he was 20 years old, he joined the St. Petersburg Academy, where he held the position of Physiology professor. At the age of 26, he was appointed chair of mathematics to replace his friend Daniel Bernouilli. From then on, his name appears in most branches of mathematics and other scientific fields, for which he published over 900 works. A mathematical genius with an exceptional memory, Euler was able to perform complex mental calculations and recite complicated mathematical calculation formulas and results by heart.