Code Cracker

Please wait until the page fully loads.

Need help? Here is a Code Cracking slide presentation.

Drag the letters on the yellow tiles above to replace their coded equivalents in the message. Correct replacements will stay in place while errors will return to the alphabet.

Click the button on the right to get a hint which may help you crack the code. There are many hints available and viewing them won't affect your score. Your score will be the percentage of letters you decoded correctly minus the number of mistakes you made.

There are three levels and you can earn a Transum Trophy for completing each level.

That is correct. You have successfully cracked the code and decyphered this . Click on the button below to claim a trophy.




Suggested Starter

Freemason's Cipher

Freemason's Cipher

Can you work out how to use the Freemason's or Pigpen Cipher? Can you find any words in the Freemason's Cipher which are symmetric? What is the longest one you can find?

Clue Challenge

Letter Clue Calculations

Letter Clue Calculations

Write down a calculation involving single digit numbers. Write the numbers in the calculation in words. Choose just one letter from each of your words and give this clue to a friend. Can your friend work out what your calculation was?

Try Texting



A code breaking exercise based on the use of a mobile phone. Unfortunately Mary's teacher did not know how to use the predictive text facility so the wrong words were sent. Can you figure out the correct answers?

Simon Kuestenmacher, Twitter

Tuesday, May 1, 2018

Neil Kaye, Twitter

Monday, February 22, 2021

Diana, Wellintn

Monday, September 18, 2023

"Your quote from Spike Milligan is incorrect. It is " There are holes in the sky for the rain to get in but the holes are small that's why rain is thin" Scans better than your alteration I think.

[Transum: Thanks Diana but are you sure? My internet searching cannot find the version you are quoting. Unless you can give me a source that shows otherwise I'll stick to the current version which Google seems to agree with.]"

Do you have any comments? It is always useful to receive feedback and helps make this free resource even more useful for those learning Mathematics anywhere in the world. Click here to enter your comments.

Another activity on the Transum website requiring you to figure out the letters used in hidden words is called Shark's Dinner? In what order should you choose letters? The obvious answer would be to find a list of the most common letters used in the English language and use this as your letter selection order.

You may be surprised to hear that this is not necessarily the best strategy. Words of different lengths will have different letter frequencies. Also when you have established whether are particular letter is or isn't in a word your next choice should be affected by that knowledge.

Tom Whipple is the science editor for The Times in London and in an eposode of the Freakonomics podcast he talked about his book How to Win Games and Beat People in which he discusses strategies that might be used when playing games similar to Shark's Dinner. Here is an extract from the podcast:

Tom Whipple's Strategies

The solutions to this and other Transum puzzles, exercises and activities are available here when you are signed in to your Transum subscription account. If you do not yet have an account and you are a teacher, tutor or parent you can apply for one by completing the form on the Sign Up page.

A Transum subscription also gives you access to the 'Class Admin' student management system, downloadable worksheets, many more teaching resources and opens up ad-free access to the Transum website for you and your pupils.

Any single letter words are likely to be 'a' or 'I'.

Two letters followed by an apostyrophe and another letter could be it's or he's.

The most common letters used in the English language are, in order, E,T,A,O and I

The most common double letters in order of frequency are ss, ee, tt, ff, ll, mm and oo.

The most common two-letter words in order of frequency are of, to, in, it and is.

The most common three-letter words in order of frequency: the, and, for, are & but.

The most commonly used words in the English language in order of frequency: The, of, and, to & in.

The most common first letter in a word in order of frequency are T, O, A, W and B.

The most common last letter in a word in order of frequency are E, S, T, D and N.

More than half of all words end with E ,T, D or S.


©1997-2024 WWW.TRANSUM.ORG