Reasoning and Mental Ability
Reasoning rewards method, not memory. Recurring types are number and letter series, analogies, coding–decoding, blood relations, direction sense, ranking, syllogism, seating arrangement and non-verbal items such as mirror images, paper folding and dice.
Method notes
- Series: test differences, then ratios, then alternating patterns; for letters convert to positions A = 1 … Z = 26.
- Coding: try simple letter shifts, reversal and position sums before assuming a complicated rule.
- Blood relations: draw a tree; never trace more than two links mentally.
- Direction: fix north and rotate. Facing south, a left turn means facing east.
- Ranking: total = rank from top + rank from bottom − 1.
- Syllogism: 'All A are B' does not convert to 'All B are A'; 'Some A are B' does convert to 'Some B are A'.
Worked example
If CAT = 24 and DOG = 26, what is BAG? Test the position-sum rule. C = 3, A = 1, T = 20 → 24, correct. D = 4, O = 15, G = 7 → 26, correct. So BAG = 2 + 1 + 7 = 10.
Traps
- Treating a stated anticlockwise turn as clockwise.
- In syllogism, accepting a possibility as a certainty.
- Ignoring the facing direction in seating puzzles, which flips left and right.
- Over-fitting a series rule to the first two terms only.