# Definition:Plastic Constant

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## Definition

The **plastic constant** is the real root of the cubic:

- $x^3 - x - 1 = 0$

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Its value is approximately:

- $P = 1 \cdotp 32471 \, 795 \ldots$

This sequence is A060006 in the On-Line Encyclopedia of Integer Sequences (N. J. A. Sloane (Ed.), 2008).

## Also known as

The **plastic constant** is also known as:

- the
**plastic number** - the
**plastic ratio** - the
**minimal Pisot number** - the
**platin number** - the
**silver number**(not recommended as there is another constant with that name) **Siegel's number**(for Carl Ludwig Siegel)**le nombre radiant**(French for**the radiant number**).

Some sources identify it with the symbol $\rho$.

## Also see

## Sources

- Piezas, Tito III, van Lamoen, Floor and Weisstein, Eric W. "Plastic Constant." From
*MathWorld*--A Wolfram Web Resource. https://mathworld.wolfram.com/PlasticConstant.html