Letter and Symbol Series: MDCAT Notes and MCQs
Number series — what to check (in order)
- Differences (constant → arithmetic progression; increasing → check second differences): 2, 6, 12, 20, 30 → diffs 4, 6, 8, 10 → next 42.
- Ratios (geometric progression): 3, 9, 27, 81 → ×3.
- Squares / cubes: 1, 4, 9, 16 (n²); 1, 8, 27, 64 (n³); n² ± 1.
- Mixed operations: ×2 + 1 → 5, 11, 23, 47, 95.
- Primes: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29…
- Alternate series: two interleaved patterns in odd and even positions.
Letter series
- Memorize positions: A1 B2 C3 D4 E5 F6 G7 H8 I9 J10 K11 L12 M13 N14 O15 P16 Q17 R18 S19 T20 U21 V22 W23 X24 Y25 Z26. Trick "EJOTY" = 5, 10, 15, 20, 25.
- Opposite letters sum to 27: A–Z, B–Y, C–X, D–W, M–N.
- Look for skips (+1, +2, +3…), reverse order, pairs (AZ, BY, CX → DW).
Coding–decoding
Find the shift rule: MEDICAL → NFEJDBM (each letter +1). Letter-value codes: CAT = 3 + 1 + 20 = 24.
PMDC learning outcomes for this unit
- Series: 5.2.1 Develop arithmetical operations as per numbers.
- Series: 5.2.2 Develop geometrical progression as per numbers
- Series: 5.2.3 Develop series / sequential orders as per letters and symbols (according to specific rules).