## 02 January 2010

### Magic and mathematics

Sunday's New York Times has a bunch of magic tricks based on simple algebra, by Arthur Benjamin.

For some magic tricks based on "deep" mathematics, check out this mathoverflow thread. Rumor has it that Persi Diaconis thinks there's no such thing, though, and he would know.

CarlBrannen said...

My students are easy to fool. They let me calculate: x/5 - x/2 = x/(5-2) = x/3 and when it doesn't get the textbook answer they are amazed.

jd2718 said...

Take a number. Square it. Drop all but the last digit. Square that. Drop all but the last digit. Multiply by the original number.

Declare the result. I can guess the number.

(unless you picked something that ends with a zero, but that doesn't happen much).

Cute application of Fermat's Little Theorem. A little math magic

Anonymous said...

Anonymous said...

Give me examples using Australia Dollar as the home currency and US Dollar as the dollar you want to buy and then exchange back to Aussie dollar. By this, you can use the current rate or any rate but please specify which side of the quote price that I should be looking at when exchange one currency to the other. And when I exchange back, which price quote should I be looking at again? Thanks.
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