21 days...
21 questions...
leading to one answer...
and one winning team.

  Ritangle is a competition for teams of students of A level Mathematics, Scottish Highers or the International Baccalaureate

  No knowledge of mathematics beyond A level Mathematics required

  For the main competition, one question is released daily for 21 consecutive weekdays. The first question was released on 9th November 2017.

  The final question unlocks an overall answer based on the solutions to all the questions

  A maths hamper prize, including a free year long subscription to Integral, and trophy for the school or college of the winning team!

  Technology can help with some Ritangle questions

Hints for question 21

We'll post any hints for question 21 here on weekdays at 0900 up until the end of the competition on 13th December.

Hint 1

All the questions are now posted Happy Puzzling!

Question 21, starts here. Missing one or two answers does not rule out solving the whole puzzle. The preliminary clue can help resolve any ambiguities with questions 1 – 20.

You may be able to solve the question 21 in a day, it may well take you longer. We may tweet/post helpful clues on the on this page (we'll post these at 0900 on weekdays if we do it) whether we already have a winner or not. We hope to announce the winner at 0900 on 13th December.

Don’t forget, we will want to see your working if you are to win! Your working to question 21 is especially important. Please don’t publicise the answer if you find it; other people will be having fun trying to find it too! Please get in touch if you want to check something. We can’t solve the puzzle for you, but we can make sure we’ve said the right thing.

Submit your overall answer!

You need to have registered your team to do this. The captain's e-mail address is required again in this form so we can check your team has been registered.

The overall answer is a string of 25 letters (no digits, spaces or other characters, and not case-sensitive).

When you submit an answer below the team captain should receive an e-mail confirming that the answer has been received. The judges will look at your answer as soon as possible and will get in touch with your team's nominating teacher if there is a possibility that your team has won!


Answer: (25 letters left)

Main Competition Questions

The answers to questions 1 to 20 are used to answer question 21.

To do this, each of your answers to questions 1 to 20 should be spelt out as text, so the answer 123 would read

onehundredandtwentythree.

You only need the first 20 characters, for example

onehundredandtwentyt.

The answers to questions 1 to 20 should then be arranged in grid form.

You do not need to solve every question to find the overall answer to Ritangle. Where there are gaps, you may be able to guess sensibly.

You will be able to submit your overall answer to Ritangle from 0900 on 7th December, when question 21 will be released and registration will close.

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2017 MEI. Integral is produced by MEI, an independent charity committed to improving mathematics education. Registered Charity Number 1058911.