Where'd e come from?

The Key Players:

John Napier (1550-1617)

John Napier a Scottish mathematician, astronomer, and physicist is known for popularizing the use of the decimal point and inventing logarithms. Within his work on logarithms published in 1618 appears the first notion of e.

Gottfried Leibniz (1646-1716)

Gottfried Leibniz a German mathematician and philosopher was the first known user of the constant in 1690.

Jakob Bernoulli (1654-1705)

Jakob Bernoulli a Swiss mathematician and scientist further developed the notion of e with his study of compound interest.

Leonhard Euler(1707-1783)

Leonhard Euler a Swiss mathematician and physicist started using the letter e to describe the exponential constant around 1727. While other letters were used, e eventually became the standard.

Why e?

Why is this special constant the letter e and not some other letter? For a while there was no standard, and researchers often used the letters b or c to represent the number. Euler was the one that started using the letter e consistently, which later became convention.

No one knows for sure, but there is spectulation on why Euler chose e. Possibly he used it because it was the next vowel after a, which he was already using for some other quantity. Others speculate that he chose e because it was the first letter of the word exponential. It is probably just a coincidence that the first letter of his name is also an e. He was a modest man who tried to give credit where credit was due.