Coding - Decoding
🔒 Log in to trackLanguage (sentence) coding with common words
🔒 Log in to trackA 'code language' writes whole sentences as code words: 'pa ka ni' for 'good morning sir'. The code words are usually jumbled (not in the same order as the words). You find a word's code by comparing sentences: a word common to two sentences has its code among the code words common to those two sentences. When the comparison leaves two choices, the code cannot be determined.
Detailed notes
What is language coding?
A whole sentence is written in a code language: 'good morning sir' becomes 'ta pa ni'. You get two or three such sentence–code pairs and must find the code of a word (or the meaning of a code).
The golden fact: the code order is usually jumbled. 'good morning' = 'ta pa' does NOT mean good = ta. Never match by position.
The intersect-and-subtract method
- Intersect. For the word you need, find every sentence that contains it. The word's code is among the code words those sentences have in common.
- Subtract. Remove codes already fixed for other words. One code left → that is the answer.
Example: 'sun is hot' = 'ta mo ri'; 'sun is bright' = 'ri ze mo'. The words 'sun is' are common, so their codes are 'ri mo' (the common code words). Sentence 1's leftover word 'hot' takes the leftover code ta.
When the answer is 'cannot be determined'
If, after subtracting everything you know, two codes still fit the word, stop. The answer is cannot be determined. Example: 'sky is blue' = 'ta pa ka'; 'sea is deep' = 'pa za la'. Only 'is' is common → is = pa. 'Blue' can be 'ta' or 'ka' — both remain possible. Picking one of them is the classic wrong move; the option 'cannot be determined' exists exactly for this.
More sentences = more information. With three well-chosen sentences every word usually gets pinned down; with two sentences some word almost always stays open.
Phrase and digit codes
- To code a phrase ('sweet home'), find each word's code, then write them in the order the phrase asks, not in any remembered order.
- Some papers use digit codes: 'come home' = '1 2', 'sweet home' = '2 3' → come = 1, home = 2, sweet = 3. The same intersect-and-subtract method works on digits.
Reverse questions ('what does pa mean?')
Work exactly the same way, then read the answer backwards: if pa = mango, then the code 'pa' means mango. The options are usually English words — check each option against your fixed mapping.
A watertight check (for practice)
For every sentence, the set of code words and the set of English words must match one-to-one: a word in the sentence ⇔ its code in the code line. If your final mapping makes any sentence inconsistent, you paired something wrongly.
Quick revision
- Never match by position — code order is jumbled.
- Intersect: word's code ∈ common codes of all sentences containing it.
- Subtract fixed codes; one left = answer.
- Two codes still possible → cannot be determined.
- Phrase codes follow the phrase's own word order; the same method works for digit codes.
Types of questions asked
Every way this subtopic shows up in exams — how to recognise it, the formula or logic to use, and a solved example.
Type 1: Two sentences, one common wordvery common2 practice Q
Two sentence–code pairs sharing exactly one word (or two) — the basic look of this subtopic.
- Find the word common to both sentences; its code is the common code word.
- In one sentence, the leftover word takes the leftover code.
- Read the asked word off your mapping.
Why it works: with one common word, the common code is forced on both sides.
Example: 'delhi is big' = 'ja pa ni'; 'mumbai is big' = 'sa pa ni'. Code for delhi?
'is' and 'big' are common → their codes are 'pa ni'. Sentence 1's leftover 'delhi' takes ja.
Type 2: Three sentences, chain eliminationcommon3 practice Q
Three sentence–code pairs; the asked word needs two subtraction steps.
- Fix codes for words common to sentence pairs (common words ↔ common codes).
- Subtract all fixed codes from the asked word's sentence.
- The last remaining code is the answer.
Why it works: each fixed code shrinks the leftovers; three sentences usually finish the job.
Example: 'train runs fast' = 'la jo me'; 'bus runs fast' = 'la jo fi'; 'fast train' = 'me jo'. Code for bus?
fast and train are common to sentences 1 and 3 → codes 'jo me'. fast also sits in sentence 1–2 pair ('la jo') → fast = jo, the code in both pairs. Then train = me, runs = la, and bus takes sentence 2's leftover fi.
Type 3: Cannot be determined (two codes left)common3 practice Q
The asked word appears in only one sentence, and two codes there remain unclaimed.
- Fix every code you can with the common-word method.
- Count the codes still possible for the asked word.
- Two possible → answer 'cannot be determined'; never guess one.
Why it works: jumbled order means both leftovers are equally likely until something pins one down.
Example: 'sky is blue' = 'ta pa ka'; 'sea is deep' = 'pa za la'. Code for blue?
Only 'is' is common → is = pa. Blue can be 'ta' or 'ka' — two codes remain → cannot be determined.
Type 4: Phrase codes and digit codescommon2 practice Q
The question codes a phrase ('sweet home') or uses digits ('come home' = '1 2').
- Find each word's code by the usual method.
- Write the phrase's code in the phrase's own word order.
- For digits, the method is identical — the tokens are just numbers.
Why it works: a phrase code is only its word codes written in the asked order.
Example: 'come home' = '1 2'; 'home sweet' = '2 3'. What is the code for 'sweet home'?
home is common → home = 2. So come = 1 and sweet = 3. 'Sweet home' = 3 2 (sweet first, as the phrase asks).
Type 5: Reverse: what does the code mean?occasional2 practice Q
The question gives a CODE and asks which English word it stands for.
- Fix the mapping word-by-word with intersect-and-subtract.
- Look up the given code in your mapping.
- Give the English word as the answer.
Why it works: the mapping is symmetric; only the reading direction changes.
Example: 'birds fly' = 'lo pe'; 'fly high' = 'pe ni'; 'birds sing' = 'lo ra'. What does 'ra' mean?
birds ↔ lo (sentences 1, 3), fly ↔ pe (1, 2). Sentence 3 leaves sing = ra, so 'ra' means sing.
Shortcut tricks
⚡ Intersect, then subtract
For a word, take the code words of every sentence that contains it (intersect), then remove code words already fixed for other words. One code left = answer; two left = cannot be determined (unless the options force it).
Example: Q. 'sun is hot' = 'ta mo ri', 'sun is bright' = 'ri ze mo'. Code for 'hot'?
'sun is' is common → 'ri mo' is common. Sentence 1 left: hot ↔ ta.
Where students lose marks
Matching code words by position — the code order is usually jumbled.
Picking one of two equally possible codes instead of answering 'cannot be determined'.
Forgetting that a code word already fixed for another word cannot be reused.
Practice sets — 12 questions
Sets of 10, mixed across the question types above. Each answer comes with a step-by-step explanation.
Topic test · 12 questions
Suggested time 8 min · wrong answers go to your mistake notebook automatically.