Coding and decoding
Compare positions systematically and verify a proposed code against every provided example.
Identify the operation#
A code may substitute one symbol for another, shift alphabet positions, reverse order, rearrange positions, or assign numeric values. Begin by aligning the original and coded forms.
If CAT becomes DBU, each letter moves one position forward. The same rule changes DOG to EPH.
Use multiple examples#
One short pair can fit many accidental rules. Additional examples reveal whether the operation is consistent or position-dependent.
Reverse accurately#
If encoding shifts each letter +2, decoding shifts -2. If encoding reverses then shifts, decoding must undo the shift and reversal in the reverse order.
Word-based codes#
In statement codes, repeated words can reveal repeated symbols. Compare complete statements and isolate common elements. Do not assign a meaning until the overlap supports it.
Common mistakes#
Avoid assuming every code uses alphabet order. Watch wraparound from Z to A, and do not mix one-based alphabet positions with zero-based counting.
Final check#
Apply your rule to all supplied examples, then encode or decode the target one step at a time. A valid answer should need no exceptions.
Key points
- Identify whether the code changes symbols, positions, order, or values.
- Compare more than one example before fixing a rule.
- Track alphabet shifts with signed differences.
- Decode by reversing the exact encoding operation.