Puzzles are an untimed educational and entertainment activity. They are not a clinical, diagnostic, standardized, or professionally recognized assessment. Solving puzzles here does not produce an IQ score and cannot be used for Mensa qualification, diagnosis, giftedness identification, educational placement, employment selection, disability applications, accommodations, legal matters, or medical decisions. Puzzle items are never used as unseen scored questions in any Novus Learn assessment.
Nothing here is timed and nothing is scored. Read the enciphered text, work the system out on paper, then check yourself against the explanation, which names the technique and shows the arithmetic step by step. Every puzzle is self-contained: the system, and the key or crib you need to recover it, is always given. Alphabet positions run A = 1 to Z = 26, and any shift running past Z wraps back round to A.
Choose one answer for each item. Keep the authored hints, answer key, and worked explanations separate until you are ready to check your work.
Start here and establish the method before moving up the ladder.
1. puz-code-and-cipher-01: One step forward · Difficulty 1
Every letter of the message was replaced by the letter one place further on in the alphabet. What was the original message?
Each letter moved one place forward.
DPME SBJO
Worked example: A becomes B.
Answer:
2. puz-code-and-cipher-02: Three places along · Difficulty 1
Each letter of a short instruction was moved three places forward through the alphabet. What did the instruction say?
Each letter moved three places forward.
DGG VDOW
Worked example: A becomes D.
Answer:
3. puz-code-and-cipher-03: Numbers for letters · Difficulty 1
Each letter of a word was replaced by its position in the alphabet, counting A as 1. What was the word?
Alphabet positions, one number per letter.
3 12 5 1 14
Worked example: 1 becomes A.
Answer:
4. puz-code-and-cipher-04: Back to front · Difficulty 1
Each word of the message was written backwards, but the words were left in their original order. What was the message?
Every word reversed; word order untouched.
NEPO EHT ROOD
Worked example: TAC becomes CAT.
Answer:
5. puz-code-and-cipher-05: Four symbols · Difficulty 1
A message was written with symbols in place of letters, using this legend: # = A, * = R, + = E, ~ = D. Each group of symbols is one word. What does the message say?
Symbol substitution, legend supplied in the prompt.
# *+~ ~++*
Worked example: * becomes R.
Answer:
Continue in order; use the worked explanations from earlier rungs when needed.
6. puz-code-and-cipher-06: The crib at the front · Difficulty 2
A shift cipher was used, but the size of the shift was not recorded. You are told that the first word of the message is THE. What does the whole message say?
Shift of unknown size; the first word is known to be THE.
YMJ UFYM NX HQJFW
Answer:
7. puz-code-and-cipher-07: The alphabet reflected · Difficulty 2
Each letter was swapped for the letter the same distance from the other end of the alphabet, so the first letter pairs with the last. What was the message?
Mirrored alphabet: first pairs with last, second with second-last, and so on.
DZIN SZMWH
Worked example: A becomes Z.
Answer:
8. puz-code-and-cipher-08: An alphabet built from a keyword · Difficulty 2
A substitution alphabet was built by writing the keyword PLANET first, then the remaining letters of the alphabet in their usual order. That row was placed under a normal A to Z row, and each letter of the message was replaced by the letter beneath it. What was the message?
Keyword alphabet: PLANET, then B C D F G H I J K M O Q R S U V W X Y Z.
IEES PS JKKJ
Worked example: P becomes A.
Answer:
9. puz-code-and-cipher-09: Half the letters gone · Difficulty 2
The spaces were stripped out of a message and then every second letter was deleted, leaving the first, third, fifth and so on. Which message produces the surviving string?
Spaces removed, then every second letter deleted.
TEODSR
Answer:
10. puz-code-and-cipher-10: A shift for digits · Difficulty 2
A reference number was disguised by increasing every digit by four, with anything past nine wrapping round to zero, so 8 became 2. What was the original number?
Each digit increased by four, wrapping past nine back to zero.
7150 3826
Answer:
11. puz-code-and-cipher-11: Two rails · Difficulty 2
The letters of a message were written along two rails, taking the first letter on the top rail, the second on the bottom, the third on the top, and so on. The top rail was then read out, followed by the bottom rail. Which message was enciphered?
Two-rail fence: top rail read out first, then the bottom rail.
SNHLNWEDEPO
Worked example: PLANT becomes PATLN.
Answer:
Continue in order; use the worked explanations from earlier rungs when needed.
12. puz-code-and-cipher-12: No crib at all · Difficulty 3
A shift cipher was used and neither the size of the shift nor any word of the message is known. The word lengths and spacing have been kept. What does the message say?
Shift of unknown size; word lengths preserved.
P ZLL H ZOPW
Answer:
13. puz-code-and-cipher-13: The mirror without a map · Difficulty 3
Every letter was replaced by its partner counted from the opposite end of the alphabet, so the letter at position n becomes the letter at position 27 minus n. What was the message?
Mirrored alphabet, no worked mapping supplied.
GSV OZHG GIZRM
Answer:
14. puz-code-and-cipher-14: Three rails · Difficulty 3
A message was written in a zig-zag across three rails, running down to the third rail and back up to the first, over and over. The three rails were then read out in order, top to bottom. Which message was enciphered?
Three-rail fence: rails read out top, middle, bottom.
BGKRNTEESIHY
Answer:
15. puz-code-and-cipher-15: Columns out of order · Difficulty 3
A message was written left to right in rows of four letters, filling three complete rows. The columns were then read downwards and sent in the order 3, 1, 4, 2. What was the message?
Twelve letters in three rows of four; columns sent in the order 3, 1, 4, 2.
OHTCEGSEELTA
Answer:
16. puz-code-and-cipher-16: Shifted, then flipped · Difficulty 3
Two operations were used on this message. Every letter was moved four places forward through the alphabet, and then each word was written backwards. What was the message?
Shift of four forwards, then each word reversed.
HRMJ ILX CIO
Answer:
17. puz-code-and-cipher-17: Positions plus three · Difficulty 3
Each letter was turned into its alphabet position, then three was added to every number. The slashes mark the ends of words. What was the message?
Alphabet positions with three added to each; slashes separate words.
21 8 4 7 / 23 11 8 / 16 4 19
Answer:
Continue in order; use the worked explanations from earlier rungs when needed.
18. puz-code-and-cipher-18: Which keyword built the alphabet · Difficulty 4
A substitution alphabet was built by writing a keyword first, dropping any letter that had already appeared, then adding the unused letters of the alphabet in order; that row sits under a plain A to Z row. The first word of the message is THE. Which keyword was used?
Keyword alphabet of unknown keyword; the message begins with THE.
TEN AIUN OMMR
Answer:
19. puz-code-and-cipher-19: The order the steps were taken · Difficulty 4
Ignoring spaces, each letter was moved forward by a repeating key of one place then four places, one then four, across the whole message. The resulting ten letters were then written out backwards. What was the message?
Repeating key of one and four places forward, then the whole string reversed.
KBFFLUODEQ
Answer:
20. puz-code-and-cipher-20: A key of two letters · Difficulty 4
The key BE was repeated across the message, ignoring spaces, and each key letter's alphabet position was added to the position of the letter beneath it, wrapping past Z back to A. What was the message?
Key BE repeated: add 2 to the first letter, 5 to the second, and so on.
OJGYCYFFYS
Worked example: A under key B becomes C.
Answer:
21. puz-code-and-cipher-21: The group that fails its check · Difficulty 4
Each group is four letters followed by a check letter. The check letter's alphabet position equals the total of the four letters' positions, with 26 taken off as often as needed to leave a total between 1 and 26. One group was altered in transmission. Which group is it?
Four data letters plus a check letter in each group.
BEADL CAGEP FLAXM GRIPX
Answer:
22. puz-code-and-cipher-22: Five bits per letter · Difficulty 4
Each letter was written as its alphabet position in binary, using five bits with the largest value on the left, so the bits stand for 16, 8, 4, 2 and 1. What was the word?
Five-bit binary, one group per letter, largest value on the left.
00011 01000 00001 10010 10100
Answer:
Continue in order; use the worked explanations from earlier rungs when needed.
23. puz-code-and-cipher-23: A key of three letters · Difficulty 5
The key CAB was repeated across the message, ignoring spaces, and each key letter's alphabet position was added to the letter beneath it, wrapping past Z back to A. What was the message?
Key CAB repeated: add 3, then 1, then 2, and repeat.
KJFHUJHNCS
Answer:
24. puz-code-and-cipher-24: The message carries its key · Difficulty 5
One letter of this ciphertext stands on its own and is not part of the message: it is the key. Its alphabet position is the number of places every other letter was moved forward. What was the message?
A shift cipher whose key letter travels inside the ciphertext.
XYNW CQN PJCN I
Answer:
25. puz-code-and-cipher-25: Two systems, one message · Difficulty 5
This message was enciphered with exactly one of two systems: a mirrored alphabet, where the letter at position n becomes the letter at position 27 minus n, or a shift of five places forward. Decide which was used, then give the message.
One of two named systems was used; the other was not.
HSLIG DZOP
Answer: