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Mathemagical Day

By Sean McLachlan
Arizona Daily Wildcat
April 19, 1999
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Leigh-Anne Brown
Arizona Daily Wildcat

"Mathemagician" Art Benjamin assures the audience that there are no tricks up his sleeves as he attempts to solve a challenging math problem yesterday as a part of Math Awareness Week. Benjamin's performance included calculating long multiplication problems, magic squares and squaring numbers all in his head while racing against a calculator.

Most people wouldn't try to multiply 96,251 by 97,463 in their heads.

But Arthur Benjamin isn't like most people.

The self-described "mathemagician" mixed math, magic and education yesterday for about 100 students and Tucson children at the University of Arizona. The event kicked off the UA's Math Awareness Week.

The mathematics professor from Harvey Mudd College in Claremont, Calif., travels around the country doing seemingly impossible problems in his head.

The trick, he said, is making big problems easy and seeing patterns behind the numbers.

"I don't want you to think you're seeing something out of 'Rain Man' here," he said. "There's a method to my madness."

With the long multiplication problem, Benjamin broke the two numbers down into their smaller components: 96,251 became 96,000 and 251 while 97,463 became 97,000 and 463.

The two parts of the first number are multiplied with the two parts of the second. The results are then added, making it much simpler than trying to do the entire problem at once, he said.

Benjamin also said he uses mnemonic devices to remember numbers while he's calculating, and he multiplies from left to right.

"You can start to say the answer while your calculating, giving the illusion that you're doing it even quicker," he said.

Benjamin also challenged audience members to find the square roots of two and three-digit numbers on a calculator while he solved it in his head.

He won every time.

By understanding mathematical patterns behind the calendar, Benjamin can listen to a spectator's birth date and rattle off the day of the week that the audience member was born.

Benjamin said he became fascinated with the structure of math at an early age. He found its internal consistency "beautiful."

"My parents always made math a game for me," he said. "That's my advice for getting kids interested in math at the beginning - make math a game."

So what is 96,251 times 97,463?

9,380,911,213 of course.

It's just simple mathematics.