Exercises from the 1st event of UCLU Maths Challenge 2009/2010

All the exercises used in the 1st event of this year's Maths Challenge can be downloaded here and here (these are Microsoft Word files each of which contains a portion of the 100 exercises used; if you can't find a particular exercise in one of the files, it is bound to be in the other). The exercises are ordered according to difficulty (from the easiest to the hardest) rather than exercise number. Solutions to the exercises will be available later.