Look at the image on the right and figure out how the numbers are related.

Then try and work out what the missing number could be.

I did originally ask how to solve the puzzle, and thanks go to Nev Rowbottom, Graeme Wood, Rachel Helliwell, Kevin Horton, Ray Sharp, Adam Cooper, Anshul Gulati, Clive Rolston, Paul Hercus, Ian Atkinson, and Matthias Rieche.    

The grid on the left has a number of blue squares, one of which contains a white spot.

To complete the puzzle you must add a further seven spots, making eight on total, such that all the spots are on their own horizontal, verticle and diagonal line.

Click here to open a new window containing the solution

As a bit of respite from the harder puzzles, here's a fairly straightforward one.  Each wheel has two pulleys, the outer having twice the circumference of the inner.  If pulley A turns at 100rpm, at what speed does pulley E turn at?

The Grid

First of all you need to figure out how the grid on the right is constructed.

Then use that information to complete the question mark slot.

I have to say that this one is a real stinker. Thanks to Rachel Helliwell of Rigby Speciality Wires for providing a reason for the answer!

The grid to the left contains a number of symbols, each representing a unique integer. There are eight sums made up from the rows and columns of the grid.

Use the seven completed sums to figure out the answer to the final sum.

Look at the image above. By moving just two of the matches, can you correct the Roman numerals sum so that it is correct?

There are at least two possible solutions.

Here's a wordy little problem.

Look at the five pairs of words in the image, and replace the first letter of each pair to form new words. Reading down the central line will give a new five letter word.

The solution...

Big and Tale are replaced by a 'P'; Nose and Tone get an 'H'; Much and Hat, can use an 'O' (awkward one, that); Vote and Heat get their first letters replaced by 'N'; while Rat and Jar get an 'E'.

Thus the answer is "phone".

The puzzle here is quite simple: These six cubes have been glued together. How many non-glued faces are there. There are no hidden cubes.

A classic puzzle loved by Mensa testers everywhere.

Another classic pattern recognition puzzle in the IQ test style.

This collection of letters can be formed into seven English words, where all the letters are used once in each word. What are those words?

Hexagons

This one is a real stinker. Give yourself a huge pat on the back if you figured it out.

Apparently, the answer is:

 but I can't figure out why.  When I find out the reasoning, I'll post it here. Email me if you know (please!).

A farmer has to ferry a fox, a chicken and a sack of corn across a river. Left unsupervised, the chicken will eat the corn and the fox will not hesistate to eat the chicken. But the boat can only carry one of them at a time. How does the farmer get them all safely across?

The answer:
Take the chicken across first, and go back to collect the corn. Take the chicken back to the first side and collect the fox. Finally go back for the chicken.