## Word frequency laws

In 1945 the linguist George Zipf observed two strange word frequency phenomena: the longer a word is, the less common it is; and the most common word is used twice as much as the second most common, three times more than the third.

## Truly large numbers

Imagine an experiment which only works one time in a thousand. If you do that experiment a thousand times, what’s the probability that it works at least once? Counter-intuitively, it’s 63.2%.

## Counting prayers

Worshippers of many different religious use beads on a string to count prayers: Catholic Christians, Muslims, Buddhists, Sikhs, Hindus, and Baháʼís.

## Pie spy

The inventor of the pie chart and the bar chart was also a secret agent who helped collapse the French revolutionary government’s economy through an elaborate counterfeiting operation.

## The hardest problem in computer science (Part 2)

The P vs. NP problem is perhaps the biggest unsolved question in computer science – but an answer would have profound implications for mathematics, cryptography, cancer research, nurse roster scheduling, and sudoku. [2 of 2]

## The hardest problem in computer science (Part 1)

The P vs. NP problem is perhaps the biggest unsolved question in computer science – but an answer would have profound implications for mathematics, cryptography, cancer research, nurse roster scheduling, and sudoku. [1 of 2]

## Girih tiles

The Darb-e Imam shrine in Iran contains an early and exciting example of non-periodic tiling that was only mathematically appreciated five hundred years later.

## Twelve days

Is Christmas Day the twelfth day of Christmas or the first? And why does it cost US\$170,298.03?

## Proof by intimidation

Mathematical proofs can be established by various means, including induction, contradiction, construction, and exhaustion. My favourite is proof by intimidation.