Seventh challenge cipher
Sixth challenge cipher
Third challenge cipher
Fifth challenge cipher
Second challenge cipher
Fourth challenge cipher
Can you crack these very difficult challenge ciphers? How might you systematise the cracking of unknown ciphers?
Scheduling games is a little more challenging than one might desire. Here are some tournament formats that sport schedulers use.
How would you judge a competition to draw a freehand square?
A weekly challenge concerning the interpretation of an algorithm to determine the day on which you were born.
A sequence of numbers x1, x2, x3, ... starts with x1 = 2, and, if
you know any term xn, you can find the next term xn+1 using the
formula: xn+1 = (xn + 3/xn)/2 . Calculate the first six terms of
this. . . .
This article explains the concepts involved in scientific
mathematical computing. It will be very useful and interesting to
anyone interested in computer programming or mathematics.
What day of the week were you born on? Do you know? Here's a way to
Can you think like a computer and work out what this flow diagram
It's like 'Peaches Today, Peaches Tomorrow' but interestingly
In this short problem, can you deduce the likely location of the odd ones out in six sets of random numbers?
However did we manage before calculators? Is there an efficient way
to do a square root if you have to do the work yourself?
Vedic Sutra is one of many ancient Indian sutras which involves a
cross subtraction method. Can you give a good explanation of WHY it
How can you quickly sort a suit of cards in order from Ace to King?
Is the regularity shown in this encoded message noise or structure?
A geometry lab crafted in a functional programming language. Ported
to Flash from the original java at web.comlab.ox.ac.uk/geomlab
When in 1821 Charles Babbage invented the `Difference Engine' it
was intended to take over the work of making mathematical tables by
the techniques described in this article.
Imagine a strip with a mark somewhere along it. Fold it in the
middle so that the bottom reaches back to the top. Stetch it out to
match the original length. Now where's the mark?
Start with any triangle T1 and its inscribed circle. Draw the
triangle T2 which has its vertices at the points of contact between
the triangle T1 and its incircle. Now keep repeating this. . . .