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Definition D169
Napier's constant

Let $!$ be the D6: Natural number factorial function.
The Napier's constant is the D993: Real number $$e : = \lim_{N \to \infty} \sum_{n = 0}^N \frac{1}{n!}$$

Let $!$ be the D6: Natural number factorial function.
The Napier's constant is the D993: Real number $$e : = \sum_{n = 0}^{\infty} \frac{1}{n!}$$

Let $!$ be the D6: Natural number factorial function.
The Napier's constant is the D993: Real number $$e : = \frac{1}{0!} + \frac{1}{1!} + \frac{1}{2!} + \frac{1}{3!} + \cdots$$

Let $!$ be the D6: Natural number factorial function.
The Napier's constant is the D993: Real number $$e : = \frac{1}{1} + \frac{1}{1} + \frac{1}{1 \cdot 2} + \frac{1}{1 \cdot 2 \cdot 3} + \frac{1}{1 \cdot 2 \cdot 3 \cdot 4} + \cdots$$