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From the people behind the Alan Turing Cryptography Competition.
Applications now open for Making Maths at Manchester 2017, a two-day event for year 12 maths students.
You are reading the website of the 2017 edition of the MathsBombe, which ended on Saturday 29th April at 11:59 pm
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Puzzle 4 Error
Posted by Andrew on Wednesday 8th February at 9:58 am
Puzzle 4 is tricky and the obvious answer is not the correct answer. Unfortunately, our original answer was not the correct answer either. This means that all the teams who have been marked correct have actually got the wrong answer. We're really sorry about this. Thanks to the teams that e-mailed with proofs and many apologies for this year's mistake, an unfortunate annual tradition. We'll try even harder to avoid errors if we run the competition again next year. Please note, however, that many of those complaining about our answer being wrong did not yet have the correct answer.

OK, as we munch our humble pie, here is what we are going to do to compensate, in the least unfair way, for our error:

At 3:30pm today (Wednesday 8th February) the website will shutdown for 30 minutes. We will delete everybody's entries for puzzle 4. The stored answer will be changed to the correct value and the website will reopen at 4pm. Everybody will have three additional attempts at the puzzle.

Teams that have already submitted the correct answer, despite the fact that it was previously marked as wrong, need not do anything. They will be awarded 15 points and marked as though they solved the puzzle at 4:00pm on 8th February. (Note that we will keep a record of original submission times in case these time differences are significant at the end of the competition.)

Teams that have not yet submitted the correct answer, or been marked correct for submitting our previous wrong answer will then have three more attempts to get the answer with the points decreasing in the usual way depending on the time since 4:00pm on Wednesday 8th.

Thanks for your forbearance and Good luck!
MathsBombe 2017 is organised by the The School of Mathematics at the University of Manchester.
Contact us via mathsbombe@manchester.ac.uk with any queries.