Douglas Hofstadter once wrote in his seminal book Gödel, Escher, Bach: an Eternal Golden Braid that it's difficult for an author to write something with a sudden, unexpected ending, because the fact that the reader is running out of pages makes it obvious well before the end that the ending must be coming soon. He suggested a way to prevent this. I'll discuss this in the context of a novel, just to make the concept clearer.

The idea is that you actually end the story partway through the book, so that you can't tell from how much remains how close you are to the end. Just filling the rest of the book with blank pages isn't good enough, because a reader can just turn back to the last bit of text and figure out that that's where the story ends. So when the story ends, you keep writing more of the events that happen afterwards. In this way you fill an extra 10 or 30 or 100 pages of the book, thus making it impossible for someone to tell where the actual end of the story is without reading it.

And in order to make it clear where the end of the story is to the diligent reader who works all the way through, you subtly change the writing in some way when the end occurs. You could change the mood or the writing style or the characters or the topic, in a way that marks a clear disconnect to the diligent reader. The reader will then know where the true end of the story occurs, and realise that everything that comes after it is just filler text to fool them into thinking that there was more to the story than there really is.

I think that's a pretty amazing idea. I'm not sure I've ever seen anyone actually do it, though.

The value of "e" is found in many mathematical formulas such as those describing a nonlinear increase or decrease such as growth or decay (including compound interest), the statistical "bell curve," the shape of a hanging cable or a standing arch. "e" also shows up in some problems of probability, some counting problems, and even the study of the distribution of prime numbers. In the field of nondestructive evaluation it is found in formulas such as those used to describe ultrasound attenuation in a material. The sound energy decays as it moves away from the sound source by a factor that is relative to "e." Because it occurs naturally with some frequency in the world, "e" is used as the base of natural logarithms.