Stephen Hawking was once told by an editor that every equation in a book would halve the sales. Curiously, the opposite seems to happen when it comes to research papers. Include a bit of maths in the abstract (a kind of summary) and people rate your paper higher — even if the maths makes no sense at all.

The 6th European Congress of Mathematics, which took place in Krakow at the beginning of July, wasn't just about mathematicians talking to each other. On the streets of Krakow maths buskers were entertaining the public, handcuffing innocent Krakowians, constructing emergency pentagons and reading minds. So what is maths busking all about? We caught up with Sara Santos, the director of the project, and one of her volunteers to find out.

*Plus* has teamed up with the Royal Society Summer Science
Exhibition 2011 to reveal the maths behind some of the science on show. We have chosen two exhibits from this year's participants and produced
postcards for people to pick up at the stand, accopmanied by *Plus* articles to reveal some of the the maths behind
them. Read the articles and if you
can't make it to the exhibition yourself, you can also download pdfs
of the postcards.

Visit the front-line of science at the BA Festival of Science and hear about the million dollar world of mathematical proof