I realise that the last article on e left a loose end. It started with the attempt to find the derivative of a^x but I got so distracted by the other amazing results that cropped up on the way, that I never managed to finish what I had started. I correct this here:

So finally we have reached the end of our journey. As you can see, it turns out that e is very important, essential in fact for our modern mathematics. When studying the behaviour of the universe (especially in Physics) it comes up time and time and time again. Mostly because the way things move is often modelled by differential equations and e is inexorably connected to differential equations. It is an inescapable fact that this number is at least as important as pi but its importance could only ever be realised once the Calculus was invented in the 17th century.

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