Calendars were one of the earliest calculating devices developed by civilizations. Find out about the Mayan calendar in this article.

Advent Calendar 2011 - a mathematical activity for each day during the run-up to Christmas.

Rather than using the numbers 1-9, this sudoku uses the nine different letters used to make the words "Advent Calendar".

Advent Calendar 2012 - a mathematical activity for each day during the run-up to Christmas.

Advent Calendar 2010 - a mathematical game for every day during the run-up to Christmas.

NRICH December 2007 advent calendar - a new Sudoku for each day in the run-up to Christmas.

Twenty four tasks to count down to Christmas.

A mathematical challenge for each day during the run-up to Christmas.

Explore a task from our Wild site on each day in the run up to Christmas

Mathematicians are always looking for efficient methods for solving problems. How efficient can you be?

Make some celtic knot patterns using tiling techniques

Make an equilateral triangle by folding paper and use it to make patterns of your own.

It might seem impossible but it is possible. How can you cut a playing card to make a hole big enough to walk through?

You could use just coloured pencils and paper to create this design, but it will be more eye-catching if you can get hold of hammer, nails and string.

Galileo, a famous inventor who lived about 400 years ago, came up with an idea similar to this for making a time measuring instrument. Can you turn your pendulum into an accurate minute timer?

Make your own double-sided magic square. But can you complete both sides once you've made the pieces?

Make a clinometer and use it to help you estimate the heights of tall objects.

Noticing the regular movement of the Sun and the stars has led to a desire to measure time. This article for teachers and learners looks at the history of man's need to measure things.

Nowadays the calculator is very familiar to many of us. What did people do to save time working out more difficult problems before the calculator existed?

The third of three articles on the History of Trigonometry.