[Ronald Graham][1] spent his career at Bell Labs working on applied problems such as scheduling theory, but is also known for his work in Ramsey theory. In that context [Graham's number][2] held the record for many years as the largest natural number ever used in a serious mathematical proof. Such numbers are not really part of applied mathematics.


  [1]: https://en.wikipedia.org/wiki/Ronald_Graham
  [2]: https://en.wikipedia.org/wiki/Graham%27s_number