I have a machine which has four sequential cog wheels in constant mesh.

The largest cog has 168 teeth and the others have 49, 32 and 15 respectively.

How many revolutions must the largest cog make before each of the cogs is back in its starting position?

If it takes 3 minutes to boil 1 egg, how long will it take to boil 2 eggs?

Can you replace the question marks with mathematics symbols (+-/x=) and make the equation correct:

(6 ? 3) ? 2 ? (4 ? 3) = 6

Using the BrainTracker grid below, how many words can you find? Each word must contain the central P and no letter can be used twice. The letters do not have to be connected. Proper nouns are not allowed, however, plurals are. Can you find the nine letter word?

Excellent: 41 words. Good: 31 words. Average: 23 words.

What is the next number in this sequence:

1 2 4 14 21 ==?==