O nly a few numbers are so famous that they have beenassigned their own letter, in perpetuity. The magical Euler’snumber e = 2.718281 . . . is one such number. It is the limit of the sequence (1 + 1n )n as n gets larger and larger. In 2004, Google referenced Euler’s number in a most original way, when they took the company public and sold stock options. They didn’t do this in the ordinary way, through investment banks, as one might expect. Google announced an online auction, open directly to the public at large, at the end of which the target goal of 2 718 281 828 dollars was to have been reached. The powers-that-be in the investment world were stunned by the apparent absurdity and peculiarity of such a precise target amount, but many a mathematician let out an appre-

ciative guffaw. Google was right to be fascinated by the number e. It crops up everywhere in the field of sciences. It is always present, for example, in descriptions of population growth and radio-active waste. The number e appeared superficially for the first time in 1608 in the work of Scottish mathematician John Napier (15501617), the discoverer of logarithms. In 1683, Swiss mathematician Jacob Bernoulli (1654-1705) rediscovered the number e in a study of bank account growth when interest is added year after year. But it was the work of Swiss genius Leonhard Euler (1707-1783), the most productive mathematician of all times, that put the number e on the map definitively.1