Actually, e is not "Euler's Constant", it's "Euler's Number". Euler's Constant is usually written with a γ (lower case gamma) and is about 0.577 . The link below explains it and it lists several other numbers named after Euler. So to avoid confusion, I just took out his name. I also changed the index. Napier's Constant is correct, and I used that in a few places, but it's a similarly obscure term. So I gravitated toward "The base of natural logarithms, e". People should get that.