Give me any 2 digit number that ends in 5, and I’ll square it in my head! 452 = 2025 852 = 7225, etc....
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Red-Black Card Trick
Here’s a pretty easy card trick that you can do that can also be pretty surprising. Here’s how the trick...
Continue reading...Proof with Words
2 + 11 – 1 = 12. Figure 1 demonstrates a “proof with words”! Presentation Suggestions:Write the letters for two and...
Continue reading...Drunken Walker and Fly
Imagine a drunken person wandering on the number line who starts at 0, and then moves left or right (+/-1)...
Continue reading...Goldbach’s Conjecture
Here’s a famous unsolved problem: is every even number greater than 2 the sum of 2 primes? The Goldbach conjecture, dating from...
Continue reading...Kaprekar’s Constant
Take any four digit number (whose digits are not all identical), and do the following: Rearrange the string of digits...
Continue reading...Six Degrees of Separation
The word graph has two different meanings in mathematics. One involves plotting the domain and range of a function, and another is...
Continue reading...Making History by Card Shuffling
Did you know that whenever you shuffle a deck of cards, it is quite likely that you are making history?...
Continue reading...Fibonacci Number Formula
The Fibonacci numbers are generated by setting F0 = 0, F1 = 1, and then using the recursive formulaFn = Fn-1 +...
Continue reading...Inchworm on a Rubber Rope
Imagine a rubber rope one meter long. An inchworm starts at one end and travels along the rope at 1...
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