Time for a little mathemagic! Choose any five cards from a pack and show four of them to your partner. How can they work out the fifth?
Find the frequency distribution for ordinary English, and use it to help you crack the code.
How can Agent X transmit data on a faulty line and be sure that her message will get through?
This is the start of a six-part challenge.
Can you get to the end and crack the final message?
The ciphers in this challenge use some of the techniques discussed in the problems Substitution Cipher and Transposition Cipher, so you may want to have a go at those first.
Each message when decrypted gives a small clue to how the next challenge has been encrypted, and gives you a keyword that allows you to access the next challenge.
Iwt htrdcs rxewtg rwpaatcvt lxaa jht p sxuutgtci btiwds du tcrgneixdc. Wtgt pgt hdbt ixeh id wtae ndj id hdakt xi:
Pgt iwtgt pcn hxcvat atiitgh? Lwpi bxvwi iwtn qt?
Pgt iwtgt pcn hwdgi ldgsh? Rpc ndj iwxcz du pcn hwdgi ldgsh iwpi pgt jhts duitc?
Pgt iwtgt pcn pedhigdewth? Lwpi ldgsh sd ndj zcdl iwpi rdcipxc pedhigdewth? Sdth iwpi vxkt ndj pcn wxcih pqdji iwt atiitgh iwpi bxvwi qt jhts?
Uxcpaan, ndj ctts id zcdl iwt ztnldgs id prrthh iwt htrdcs rwpaatcvt. Xi lph p rdas pcs vaddbn spn lwtc X lgdit iwxh egdqatb, hd X rwdht p qgxvwi pcs rwttguja ztnldgs: gpxcqdl.
If you want to work on a computer to solve the problem, you can download this cipher as a text file which doesn't contain any line breaks.
We have created a Cipher Challenge Toolkit with some tools to help you crack different types of code.
Once you've decrypted this message, you should have a keyword.
You can access Part 2 of the Cipher Challenge at http://nrich.maths.org/???
by replacing the ??? with the keyword.