Move over three-card monte, there's a new hustle being played on Britain's streets, a game in which street performers entice passersby, especially youngsters, with the chance to win £20.
The odds are stacked against him, but Cory, a schoolboy from south London barely into his teens, didn't know that as he played busker Rufus Roberts for the cash on a recent morning in London's King's Cross neighbourhood.
The two must took turns removing one, two or three of the dozen clothes pins clipped to an assistant's shirt, including one holding the bill, which must be removed last.
With four pins remaining, Cory's friends urged him to take two, which he did. Mr. Roberts took the final two and kept the money.
The boy berated his friends for giving him the wrong advice, not realizing that he had just been given a mathematics lesson in number patterns by Mr. Roberts, part of a small but growing cadre of university undergrads, doctoral students, teachers and performers trained in the emerging art of math busking.
Sara Santos, one of the movement's founders, said they're using methods borrowed from traditional street performers to spread the love of math in outdoor shows as well as the classroom.
"Buskers deal with that indifferent audience that mathematicians are used to, so we thought we'd learn techniques that buskers use to capture the audience," said Ms. Santos, a fellow at the Royal Institution of Great Britain, a charity dedicated to scientific education and research.
"We thought we'd use the same skills to convey mathematics in an interesting and engaging way."
The group conceived of math busking as a fun way to get people interested in mathematics, but the need to attract more British students to the study of numbers gained urgency after a report earlier this month that found pupils are discouraged from further study because of poor teaching.
The report by the Royal Society, Britain's national science academy, found about half of Britain's 17,000 primary schools lack specialist science and math teachers and recommended tripling their numbers.
At a recent fair in London aimed at encouraging students to pursue careers in science, technology, engineering and math, Mr. Roberts, a first-year undergrad studying math, and fellow trainee math busker Katie Steckles, who's doing a PhD in math, got a chance to try out their act.
"Shout if you love maths!" the pair yelled out to groups of teens on the street in a bid to get their attention before they entered to register for the exposition. They wore bright yellow shirts that said "Maths Busking."
Schoolchildren gathered around as Ms. Steckles started out by demonstrating how to tie a long strip of paper into a pentagon, which she said would come in handy "if you've got a pizza, for example, and you want to cut it into five pieces."
Mr. Roberts tried out a "mind-reading" game using numbers on cards to guess the birthdays of volunteers.
In one crowd-pleasing game, Zeeman's Ropes, two youngsters tied together with ropes twisted and contorted themselves to get free before being shown how to do it using a simple trick.
Molly, a 13-year-old from south London, also tried and failed to win the £20 from Mr. Roberts in the clothespin game.
"It taught you different ways of learning the different maths and it made it more fun and interactive," she said.
To the casual observer, the math lessons to be gleaned from a performance may be hard to discern. But Ms. Santos and her fellow math buskers say that's okay, audience members don't necessarily need to come away from a performance learning anything at all.
Ms. Santos said the buskers stick to a few key principles, foremost among them being the need to engage, not alienate, the crowd. Second, the math used must be entertaining in its own right, so magic tricks and the like are discouraged.
"You won't see us juggling chainsaws," Ms. Santos said.
But there is one key difference so far between math buskers and their more traditional counterparts. They don't ask for money - yet.
"Our reward has been to engage people and share our passion for mathematics," she said.
Special to The Globe and Mail
GAMES MATHEMATICIANS PLAY
Mind Reading: Five cards with different sequences of 16 numbers, from 1 to 31, are shown to a volunteer, who picks out the ones that contain his or her birth date. Simply by being told which cards it is on, for example the second and fourth cards, the busker is able to tell the exact birth date.
The first numbers on each card are 1, 2, 4, 8 and 16, a doubling pattern known as powers of two. Adding up the first numbers on the chosen cards will give the birthday. Say you're birthday is on the 20th. That number is found on cards 2 and 4. The first numbers on those cards are 4 and 16, and 4+16=20.
This game demonstrates powers of two, which is two multiplied by itself a certain number of times, as well as binary numbers.
Zeeman's Ropes: Take two volunteers and tie each person's wrists together with a length of rope that's also looped around their partner's rope, linking them together. They must separate themselves without cutting the ropes or untying the slipknot on each wrist. It may seem impossible; twisting or contorting your body to try to get free certainly won't work. But you may notice that the rope is not tied tightly around the wrists and if a loop of rope from one person's rope is pushed through the other's wrist hole and passed over the hand, it easily slides free.
This game is used to demonstrate topology, the mathematical study of the fundamental shapes of objects that retain their properties even when deformed.