Fast economic indicators.

Faced with an economic crisis as large and rapid as that precipitated by the COVID-19 pandemic, economists have turned to new 'fast indicators' based on big data, as Andy Haldane and Shiv Chowla of the Bank of England explain.

"Metodo rapido" for finding real quadratic fields of class-number 1.

The authors state and prove a rapid criterion to determine whether the class-number of certain real quadratic fields is 1.

Problems on periodic simple continued fractions.

Let N be a positive non-square integer and a(1),a(2),...