The Dottie number is the name given by Kaplan (2007) to the unique real root of , namely 0.739085... (Sloane's A003957). It was named after a French professor who noticed that whenever she typed a number into her calculator and hit the cosine button over and over, the result always converged to this value.

This root is a simple non-trivial example of a universal attracting fixed point.

The Dottie number gives the almost integer

(L. A. Broukhis, pers. comm.).

Kaplan, S. R. "The Dottie Number." Math. Mag. 80, 73-74, 2007.

Sloane, N. J. A. Sequence A003957 in "The On-Line Encyclopedia of Integer Sequences."

CITE THIS AS:

Weisstein, Eric W. "Dottie Number." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/DottieNumber.html