Math Quiz
The equals sign has an inventor and a birthday, like most symbols we take for granted.
A math quiz with answers that needs no calculator. It is about where numbers, symbols and proofs come from and the people behind them, so curiosity counts for more than speed at arithmetic.
Did you know?
- Pi Day is celebrated on 14 March because the date can be written 3/14, matching the first digits of π. It was first held in 1988 at a science museum in San Francisco, where staff and visitors marched around a circular room and then ate fruit pies.
- The Hungarian mathematician Paul Erdős wrote around 1,500 papers with more than 500 co-authors, travelling from one colleague's home to the next with a single suitcase. Mathematicians still measure their 'Erdős number': one if they wrote a paper with him, two if they worked with such a person, and so on.
- The word 'mathematics' comes from the Greek mathema, which simply meant 'something learned'. For the followers of Pythagoras it covered four subjects: arithmetic, geometry, astronomy and music, since musical harmony was understood as a matter of ratios between whole numbers.
Where mathematics comes from
People were counting long before they were writing. A baboon bone found at Ishango in central Africa, about 20,000 years old, carries rows of deliberate notches that look like a tally. Written mathematics appears with the first cities: Egyptian scribes around 1550 BC copied a papyrus of worked problems about sharing bread, measuring fields and finding the slope of a pyramid.
The idea of proof
What set Greek mathematics apart was the demand that every statement be proved from a few agreed starting points. Around 300 BC Euclid gathered the geometry of his day into thirteen books known as the Elements, each result resting on the ones before it. The work was used as a textbook for more than two thousand years. In 1976 the idea of proof was stretched again, when the four-colour theorem about maps became the first major result to be proved with the help of a computer.
Symbols are newer than you think
For most of history, calculations were written out in words. The plus and minus signs first appeared in print in a German book on commercial arithmetic in 1489. The multiplication cross dates from 1631 and the division sign from 1659. Before these symbols spread, a problem that now fits on one line could fill half a page, and mathematicians in different countries often could not easily read each other's work.
Problems still open
Mathematics is far from finished. In 1742 Christian Goldbach suggested that every even number greater than two is the sum of two primes; computers have checked enormous numbers, but no one has proved it. In 2000 a private institute offered a million dollars each for seven famous unsolved problems. Only one has been settled so far, and the mathematician who solved it, Grigori Perelman, turned the money down.