On the day of his inauguration on 20 January, US President Donald Trump promised to deliver the “most extraordinary first 100 days of any presidency in American history”. For decades, the 100 ...

Numbers are a fundamental part of our everyday lives, shaping the way we measure, trade, and keep track of time. While most ...

Combinatorics, or at least part of it, is the art of counting. For example: how many derangements does a set with n n elements have? A derangement is a bijection with no fixed points. We’ll count them ...