A student talked about Kaprekar’s constant (6174) during their my favorite presentation. Really cool. Steps (from wikipedia): Take any four-digit number, using at least two different digits. (Leading zeros are allowed.) Arrange the digits in descending and then in ascending order to get two four-digit numbers, adding leading zeros if necessary. Subtract the smaller number […]
It’s midterm week at school, and James Tanton threw out two interesting questions in two days. I spent a little time programming “solutions” to these problems (not solutions, just verifications for an infinitesimally small portion of the natural numbers). Problem One: Start with a prime, square it, and add 4. Repeat. (eg 3->13->173->…) Must eventually […]
Linked from the Visualizing Math blog, a cool simulation of bouncing balls with randomized gravity and bouncing coefficients. Forward Slash Reality Check out the video too.
@fawnpnguyen whoa. Need to try and make this. — Dan Anderson (@dandersod) June 4, 2013 I started off and used VPython to create the fractal, but it was slow and buggy. Here’s a movie of my first attempt. When you click you create a new “seed” for the fractal to start. So I rewrote it […]
Intro to Computer programming worked at calculating digits of pi today. The actual algorithms aren’t too bad, but getting more than the standard number of digits from a double is a bit trickier. Here’s a program that calculates pi using: Bailey–Borwein–Plouffe formula Bellard’s formula and Chudnovsky algorithm Holy smokes is Chudnovsky algorithm’s fast! Plouff Bellard Chudnovsky Iteration […]
Number theory nugget: 357686312646216567629137 is a prime number which remains prime after removing any number of digits from the left side! — Maths World UK (@MathsWorldUK) March 4, 2013 Otherwise known as left-truncating primes with every suffix prime and no digit are zero. Here is the whole sequence. It was proven that 357686312646216567629137 is the last […]