There are two completely different definitions of Cayley numbers. The first and most commonly encountered type of Cayley number is the eight elements in a Cayley algebra, more commonly known as octonions. A quantity which describes a Del Pezzo surface is sometimes also called a Cayley number (Coxeter 1973, p. 211).

# Cayley Number

## See also

Complex Number, Del Pezzo Surface, Octonion, Quaternion, Real Number## Explore with Wolfram|Alpha

## References

Coxeter, H. S. M.*Regular Polytopes, 3rd ed.*New York: Dover, 1973.

## Referenced on Wolfram|Alpha

Cayley Number## Cite this as:

Weisstein, Eric W. "Cayley Number." From
*MathWorld*--A Wolfram Web Resource. https://mathworld.wolfram.com/CayleyNumber.html