Coding-Decoding is a rule-detection machine: a word goes in, a hidden transformation runs, a code comes out. Learn to spot the rule that survives every letter.
Every question is the same shape - input, hidden rule, output. These nine rule families teach you to recognize which rule is running.
A=1 to Z=26, vowels, and the M/N midpoint anchors.
Constant, alternating, increasing, and cyclic shifts.
Mirror pairs A↔Z where positions add to 27.
Letters unchanged - only their order moves.
Sum, product, position, length and place-value codes.
Build a mapping key: letters ↔ @, #, %, $.
Match common words to common code tokens.
Separate layers; apply rules only when conditions hold.
Mini test + alphabet-strip cheat sheet to lock it in.
Every code belongs to one of these. Tap through to see the rule, what it guarantees, and the trap that catches most learners.
The base tool: each letter has a number, A=1 up to Z=26. Vowels sit at 1, 5, 9, 15, 21; M and N mark the midpoint. Use it as one lens - not the only one.
Select a coding rule, run it on a sample word, and watch each character transform so the hidden pattern becomes visible instead of guessed.
Do not guess the pattern - prove the rule, then apply it cleanly. This loop works on every coding type.
Write input and code in two aligned rows so every position lines up. Identify the coding type first.
Test the easiest rules first: shift, reverse, position-value, rearrangement, sum, substitution.
Check the rule across every letter, word, or example. Reject any rule that works only once.
Run the verified rule on the target - or reverse it if the question asks you to decode.
Confirm against the options and the direction: did they ask to encode or to decode?
Name the family in the first five seconds and you already know which rule to test first.
One per major rule family. Step through the reasoning - the answer locks on the final step.
Tap any card to flip from the wrong instinct to the correction.
Small disciplines that make the rule visible instead of guessed.
Write original and code in two aligned rows. Most patterns become visible when positions line up.
For letter codes, write +1, +2, -1 above each position. The sequence reveals the rule.
If every original letter is still present, stop hunting shifts - it is rearrangement.
Use position values when the code clearly suggests number logic - not by reflex.
In coded language, underline common words and circle common tokens to match them.
Before answering, confirm whether they want the code, the original word, a missing code, or a language meaning.
Mixed difficulty, no timer. Every answer comes with a worked explanation and a diagram.
The alphabet strip plus the rules that crack most codes.
| Family | Signal | Example |
|---|---|---|
| Shift | letters look close | BANK→CBOL (+1) |
| Reverse | pairs sum to 27 | A↔Z, M↔N |
| Rearrange | same letter set | TRAIN→NIART |
| Number | code is digits | TIGER→59 |
| Symbol | @ # % $ | A=@, B=# |
| Language | word↔word | blue=mi |
Practice the hard stuff, queue the next topic, or revisit what tripped you up.
