Visualising 1 × 10 90 as the number of particles in the universe was seen as a sort of upper limit for all practical purposes for numbers(9 August, p 28). Why bother with infinity? I think we are ...

Sharon Hewitt Rawlette has written an excellent compendium of coincidence stories with explanations and uses, The Source and Significance of Coincidences. In this guest editorial, she takes apart the ...

1 × 10 90 seems very small compared with the useful numbers used to generate cryptography keys. Given that such numbers are routinely involved in calculations with practical real-world applications, ...