# 'Special' Numbers

• $$0$$
• $1$

• $\sqrt2$
• $\phi \ or\ (\frac{\sqrt5+1}{2})$
• $i\ or\ \sqrt{-1}$

• $\tau\ or\ 2\pi$

• $\infty$ (Thanks to Jeff Giff)
• $W(1)$ (the solution to $xe^x=1$ (Thanks to James Watson)

• $299792458$ (the speed of light in a vacuum in $\frac{m}{s}$)
• $\approx 6.67408 \times 10^{-11}$ (the universal gravitational constant in $\frac{m^3}{kg \cdot s^2}$)
• $\approx 1.616255 \times 10^{-35}$ (the Planck length in $m$) (Thanks to James Watson)
• $\approx 5.39121\times 10^{-44}$ (the Planck time in $s$) (Thanks to James Watson)

If there are other numbers that you think should be added to this list, please comment.

Note by Lâm Lê
10 months ago

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There are many numbers like c, g and more that you can add @Lin Le. C is the speed of light, and g is the universal gravitational constant.

$\infty$

- 10 months ago

$\Omega$ which is the solution to $xe^x=1$ (can also be expressed as $W(1)$ where $W(\cdot)$ is the Lambert's W Function/product log)

- 10 months ago

also the Planck length/time

- 10 months ago

How would you put Planck units as numbers?

- 10 months ago

normal units of measurement. for example: $1 \text{ Planck Length } \approx 1.616255×10^{-35} \text{ meters, }1 \text{ Planck Time } \approx 5.39 \times 10^{-44}\text{ seconds}$

- 10 months ago