The challenges are published on Thursdays at 3pm. There are 9 rounds and the schedule is published on the Challenge page
NOTE: all times stated on the site refer to current UK time. The clocks change back from British Summer time to GMT at around 2am on Sunday October 27th and our competition clock resets with that.
Please also note that Challenge 3 lasts two weeks, not because it is harder than all the others, but to accommodate as many half terms as possible (and to give you all a rest before the main competition starts)! We know that not all schools have the same dates, and it is impossible to accommodate them all, we hope you understand. It is possible for Team Captains to submit their solutions from anywhere with internet access so they should still be able to take part if their school is not open, and the Team Captain can always delegate that role (using the team page) if they are going to be away. In the past Challenges 6 or 7 have often also lasted two weeks, but, having extended the competition in the last couple of years, we have made them just one week long. You still have a month for the Mega Challenge, round 9.