Once you've run 26 miles of your first marathon you have in front of you only 385 of the toughest yet most beautiful yards you'll ever run.

The modern Roman (or English) alphabet has 26 characters. There used to be only 25, until the letter 'J' came along in the 14th century. Since 1917, Norwegian (and Danish since 1950) has had 29 letters – the 26 of English plus 3 extra characters.

Now, most people think of our world as being 3 dimensional (3D).

In 1905, Einstein convinced us to think of time as the 4th dimension of our world and the universe. He showed that time and the 3 dimensions of space were intimately connected.

But in the 1960s we saw the emergence of "string theory" that suggests there are more than 3 dimensions of space but that these extra dimensions are so small we can't see them in our everyday lives.

To help you understand this, people sometimes use an analogy of a garden hose that from a long way away looks just like a 1-dimensional line but up close it's possible to move along the line but also actually be moving in other dimensions, for example, a spiral around its edge. Similarly, other dimensions of space might be very tightly "twisted together" and hard to see.

The original version of string theory was called "bosonic string theory" and suggested the universe is actually composed of – you guessed it – 26 dimensions of spacetime.

A variation on the magic square is the magic star of David. There are 80 different magic stars of David that arrange the numbers 1 to 12 in grids like the ones below.

There are 6 rows and each entry is involved in 2 rows so it should be obvious that if all rows add up to the same number, that number will be [(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12) + (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12)] divided by 6, giving us a magic constant of 26 for our stars.

You can find the answers here

Adam Spencer's Big Book of Numbers, Xoum, $29.99. Ebook, $14.99, www.xoum.com.au