Puzzle
Hexagonal graph

Magic 19

Number the dots so that each line of three adds up to 22.

Article

Time to go retro

A model of backward causation in which the future affects the past could help unite quantum mechanics and general relativity – and satisfy a challenge thrown down almost a century ago by Arthur Eddington.
Article

The cosmic family tree

Mapping the ancestral history of spacetime in an effort to unite quantum mechanics and general relativity.
Article

Is gravity time's archer?

A new model argues the forces between particles in the early universe loosed time’s arrow, creating temporal order from chaos.
Article

The 36 officers problem

Euler may not have cracked this problem completely, but it led to a lot of important work, including on what we today know as sudoku.
Article

The knight's tour

Can you move a knight on a chessboard so that it visits every square exactly once? Euler was one of the first to analyse this problem systematically, but some questions about it are still open today.
Article
Bridges of Königsberg

The bridges of Königsberg

Can you find a path through on this city map that crosses every bridge exactly once? Euler's answer to this problem started off the filed of graph theory.

Collection

Five of Euler's best

Five favourite problems inspired by Leonhard Euler, one of the greatest mathematicians of all time.
Article

Primes without 7s

James Maynard, one of the prize winners at the European Congress of Mathematics 2016, is counting primes that don't have 7s in them. But why?