https://b.hatena.ne.jp/entry/mathworld.wolfram.com/e.html The constant is base of the natural logarithm. is sometimes known as Napier's constant, although its symbol () honors Euler. is the unique number with the property that the area of the region bound... https://b.hatena.ne.jp/raycy/20150110#bookmark-1190127 2015-01-10T00:49:50Z https://b.hatena.ne.jp/labunix/20120723#bookmark-1190127 2012-07-22T15:16:21Z