Mathemagician: Professor Arthur Benjamin

Reading Time: 4 minutes

By Fiona Ting (24S06A)

Why was Math class so long? The teacher kept going off on a tangent!

Luckily for the audience, “Mathemagician” Professor Arthur Benjamin went off tangent plenty during his sharing on 24 March 2023 in LT2 (the location had been changed to fit the sheer number of people who had signed up)—at least in relation to the JC Mathematics syllabus. In a world where many people see mathematics as dry and uninteresting, Professor Benjamin had done the seemingly impossible: found a way to make it exciting.

Before the show began, Mr Harapan Ong provided some context by introducing students  to Professor Benjamin. For the last thirty years, Professor Benjamin had presented his highly acclaimed show incorporating both maths and magic to thousands of audiences all over the world. Listed by Princeton Review as one of America’s Top 300 Professors, Professor Benjamin had also been the recipient of many other equally prestigious awards. 

Interestingly, this was not Mr Harapan and Professor Benjamin’s first meeting: they had actually met decades ago. As proof, Mr Harapan displayed a picture of his younger self clad in a Batman sweater and standing next to Professor Benjamin, to much exclamations of surprise from the audience. They had struck up a friendship that lasted through the years, and Mr Ong was the one who had invited Professor Benjamin to speak at this event.

Starting the show off on an engaging note, Professor Benjamin requested for a volunteer from the crowd to assist him in a ‘real’ magic trick. It did not take much persuasion – enthusiastically, a student raised his hand.

“Pick a card, any card from this imaginary deck.” Professor Benjamin theatrically waved his hands to mime a deck of cards. To much bemusement from the audience, he ‘vanished’ the imaginary card.

“What was the card you had in mind?” he asked the volunteer. With wide eyes, everyone watched as he took out a real deck of cards, and in it, the only card flipped face-up was the 6 of hearts—the volunteer’s chosen card. 

This short trick encapsulated the essence of Professor Benjamin’s success in his fascinating and entertaining exploration of the intersection between mathematics and magic – engaging performance style. The magic trick that captured everyone’s attention was just the beginning of Professor Benjamin’s exciting demonstration.  

Starting off the mathematics segment of his show with a request for students to pull out their calculators, Professor Benjamin humorously asked them to “test if the calculators were in working condition” by multiplying random two digit numbers by each other. He quickly impressed the crowd by promptly providing them with the answers—his calculations were (obviously) perfect and even the famously swift Rafflesian typists were no match for his mental calculation speed.

The volunteers armed with their calculators.

Apparently, this had been child’s play. Stepping up the game, he asked the audience to multiply any 4 digit number with any 3 digit number. With the answer, they could read out any digits in the six or seven digit number, omitting one, in any order. The goal was for him to guess which number was omitted.

For example, if an audience member decided to multiply 9999 by 129, the result would be 1,289,871. Of those 7 numbers, the only information he would be given was any 5 of the  numbers, not in order: in this case, 891178. He would then be required to inform the audience that the missing answer is 2.

Much to the amazement of the audience, this seemingly impossible task was completed impeccably. Professor Benjamin then proceeded to perform several impressive mental calculations such as completing massive magic squares (sudoku on steroids) within minutes (it took this writer more than three hours to complete this mentally) and finding the day of the week regardless of year, month or date (a great number of audience members volunteered their birthdays).

An example of a 5 by 5 magic square made up of more than 13 million 3 by 3 normal magic squares: Try to find the relationships between the numbers!

The questions during the Q&A segment could be neatly summarised in one word: “how?” Smiling, Professor Benjamin graciously explained his methods: he simplified the complex calculations, which made it easier for him to mentally calculate and obtain his complex answer, using his own formulas that he previously developed. He shared that mnemonics are key to helping him remember the calculations, as he codes individual processes with letters or numbers.

Through presenting mathematics in this novel way, Professor Benjamin hopes to inspire a new generation of mathematicians. “[My show] is not to show how smart I am, but how smart [the students] can be,” he quipped when asked about his purpose. 

In a world where we are increasingly reliant on technology for even the simplest calculations, the usefulness of mental math is often overlooked. While Professor Benjamin’s  Mathemagic performance is certainly impressive, it is his underlying message that feels more significant: not only is math useful, it can also be beautiful and fun—and can hopefully inspire an increase in the H3 Math enrolment next year. 

464230cookie-checkMathemagician: Professor Arthur Benjamin


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