Name


Name	Symbol	Value
Archimedes' constant or Ludolph's number. Pi.	$\pi\,\!$	$\lim_{n \to \infty}\frac{P_{n}}{d}\,\,$ $\approx 3.14159\,\,26535\,\,89793\,\,23846\,\,26433\,\,83279\,\,50288\,\,41971\,\,\!$
Napier's constant. Base of Natural Logarithms.	$e \,\!$	$\lim_{n\to\infty} \left(1+{1\over n}\right)^n\,\,$ $\approx 2.71828\,\,18284\,\,59045\,\,23536\,\,0287\,\!$
Pythagoras' constant. Square root of two.	$\sqrt {2} \,\!$	$\approx 1.41421\,\,35623\,\,73095\,\,04880\,\,16887\,\,24209\,\,69807\,\,85696\,\,71875\,\,37694\,\!$
Theodorus' constant. Square root of three.	$\sqrt {3} \,\!$	$\approx 1.73205\,\,08075\,\,68877\,\,29352\,\,74463\,\,41505 \,\,87236\,\!$
Euler-Mascheroni's constant. Gamma.	$\gamma\,\!$	$\lim_{n \rightarrow \infty } \left[ \left( \sum_{k=1}^n \frac{1}{k} \right) - \ln(n) \right]$ $\approx 0.57721\,\,56649\,\,01532\,\,86060\,\,6512$
Apéry's constant.. Zeta(3)	$\zeta(3)\,\!$	$\sum_{k=1}^\infty\frac{1}{k^3}=1+\frac{1}{2^3} + \frac{1}{3^3} +\frac{1}{4^3} +\frac{1}{5^3} +\ldots$ $\approx 1.20205\; 69031\; 59594\; 28539\; 97381\;61511\,$
The Golden Ratio. Phi	$\varphi\,\!$	$\frac{1+\sqrt{5}}{2}$ $\approx 1.61803\,\,39887\,\,$
Natural logarithm of two.	$ln2\,\!$	$\sum_{k=1}^\infty\frac{(-1)^{k-1}}{k}=1+\frac{-1}{2} + \frac{1}{3} + \frac{-1}{4} + \frac{1}{5} + \ldots\,$ $\approx 0.69314\;71805\;59945\;30941\,72321\;21458\;17656\,$
Delian's constant. Cube root of two.	$\sqrt[3] {2}\,\!$	$\approx 1.25992\;10498\;94873\;16476\;72106\;07278\;22835\;$