A portrait of mathematician Leonhard Euler by the painter Jakob Emanuel… (Wikimedia Commons )

Leonhard Euler, a Swiss mathematician who continued to work on complex equations from memory even after he went blind, is honored in Monday's Google Doodle on the 306th anniversary of his birth.

Euler, who wrote nearly 900 books over the course of his career on topics such as lunar motion, optics, acoustics, algebra, calculus, geometry and number theory, is one of the most prolific and important mathematicians of the 18th century, and possibly of all time.

He was so prolific that a St. Petersburg, Russia, academy continued to publish his unpublished works for at least 30 years after his death in 1783. And his work was so wide ranging that "Euler's Theory" can mean something different depending on what discipline you are in.

Today's doodle celebrates some of Euler's most famous equations, including his polyhedral formula (V-F+E=2). You'll also find a graphical representation of a polyhedron that is spinning inside one of the "O's." If you mouse over the doodle, you can spin it around.

**PHOTOS: Google Doodles of 2013**

Born on April 15, 1707, in Basel, Switzerland, Euler was first taught mathematics by his father, a Protestant minister. He started attending the University of Basel in his early teens and published his first scientific paper in 1727 when he was just 19. That same year, he took second place in the Grand Prize of the Paris Academy for a paper on the best arrangement of masts on a ship.

After graduating from the university, Euler went to the St. Petersburg Academy of Sciences in Russia, where he worked on projects dealing with cartography, magnetism, fire engines, machines and ship building, according to an online biography of Euler posted to the University of St. Andrew's in Scotland's website. The cartography work probably led to Euler's sight problems, which started in 1738.

In 1731, he was invited to live and work in Berlin by Frederick the Great. Euler worked there for 25 years, writing books on the calculation of planetary orbits, shipbuilding and navigation, and calculus variations. But he ultimately returned to St. Petersburg in 1766, where he soon went completely blind.

Euler was not deterred by losing his vision, however, and half of his total works were completed after he lost his sight.

Euler was married twice and had 13 children, although only five survived their infancy.

He has said that some of his best ideas came to him while holding a baby, and he often worked with children playing underfoot.

[**For the Record**, 5:08 p.m., April 15: An earlier version of this post included a few misspellings of Euler's last name. It has since been corrected.]