Coded Blood Relations and Symbol Decoding

Coded blood relation dresses the same family tree in symbols like plus, minus, multiply and divide, or in long dotted expressions such as 'A + B − C'. It looks harder than plain blood relation, but it is actually more mechanical: once you decode each symbol into a relationship, you draw the same tree and read the answer. SBI Clerk usually sets one such question, and it is fully scoreable if you handle the symbols in the right order rather than left to right.

The Standard Symbol Meanings

Most papers define the operators in the question itself, so read the key first and never assume. A common scheme is: 'A + B' means A is the father or parent of B, 'A − B' means A is the child of B, 'A × B' means A and B are siblings, and 'A ÷ B' means A and B are a married couple. The exact meanings change from paper to paper, so the discipline is to copy the given key down before touching the expression.

Read Right to Left

The golden rule for a chain like 'P + Q − R' is to evaluate it from the right, because each symbol connects the letter on its left to the whole group on its right. Start with the last pair, fix that relationship on your tree, then attach the next letter, and so on until P is placed. Trying to read a long coded chain left to right is what makes candidates misplace a generation and pick a wrong option.

For 'A op B', the symbol always describes A's relation to B — decode each pair, then link them

Solved Example

Example: If 'A + B' means A is father of B, and 'A × B' means A is sister of B, then in 'P + Q × R', Q × R makes Q the sister of R, and P + Q makes P the father of Q. So P is also the father of R — P is R's father.

✗ Evaluating 'P + Q × R' as P plus Q first, ignoring the key  |  ✓ Decoding each symbol into a relation, then building the tree

Decoding 'A is B's ...' Sentences

A related SBI Clerk format drops symbols and instead asks which coded expression matches a plain sentence such as 'A is B's maternal uncle'. Here you work backwards: translate the sentence into tree steps — A is the brother of B's mother — then convert each step into the operator the key provides, and match the resulting chain against the options. The trick is to break the compound relation into its atomic links before you look at the answer choices, because each option is really a sequence of those atomic links written in code. If 'maternal uncle' means 'mother's brother', you need a mother link and a brother link in that order; any option missing either link, or ordering them wrongly, is eliminated at a glance. Practising this translation both ways — code to relation and relation to code — is what makes the whole coded family fast, because you stop treating the two formats as different questions and see them as one tree wearing two costumes.