Each trick says when to use it, why it works and when it fails. Formula tricks are checked by code over their whole range.हर ट्रिक बताती है कि उसे कब इस्तेमाल करें, वह क्यों काम करती है और कब नहीं। सूत्र वाली ट्रिक्स को कोड से उनकी पूरी रेंज पर जाँचा गया है।
Exam strategyपरीक्षा रणनीतिRarely taughtकम सिखाई जाने वाली✓ Checked on 270 cases✓ 270 मामलों पर जाँची गई
The series ladder: six checks in a fixed order
Use it when:कब इस्तेमाल करें: Any number series, missing term, wrong term, or a number analogy or odd-one-out that hides a pattern.
Differences constant? (arithmetic)
Differences of differences constant? (quadratic growth)
Ratios constant? (geometric)
Each term = previous × a + b? Find a from two jumps: a = (t₃ − t₂)/(t₂ − t₁).
Near squares or cubes? Compare with n², n³ and check ± a small constant.
Split odd and even positions: two simpler series interleaved.
Stop at the first check that explains every term, then verify it on the last term too.
Why it works, and when it failsयह क्यों काम करती है, और कब नहीं
Why:क्यों: Exam setters build series from a handful of rules. Checking them from cheapest to costliest finds the rule with the least arithmetic, and step 4 turns the guess “× something + something” into a calculation.
Limits:सीमाएँ: Rare series mix two operations alternately (×2, +3, ×2, +3). If all six checks fail, try alternating operations on consecutive terms.
Mental mathsमानसिक गणित✓ Checked on 26 cases✓ 26 मामलों पर जाँची गई
Opposite letters add up to 27
Use it when:कब इस्तेमाल करें: Codes like A↔Z, B↔Y, or “position from the right”.
Position + opposite position = 27.
Memory pairs: AZ, BY, CX, DW, EV, FU, GT, HS, IR, JQ, KP, LO, MN.
Exampleउदाहरण
Opposite of R (18)?
→ 27 − 18 = 9 → I
Why it works, and when it failsयह क्यों काम करती है, और कब नहीं
Why:क्यों: Reversing the alphabet maps position p to 27 − p.
Limits:सीमाएँ: Only for the full 26-letter alphabet.
Solved examplesहल किए गए उदाहरण
Answers and full solutions are shown. Hide them to test yourself first.उत्तर और पूरे हल दिखाए गए हैं। पहले खुद को परखने के लिए इन्हें छिपाइए।
Example 1उदाहरण 1 · Letter series · Easyआसान
Find the missing term: F, I, L, O, R, ?
T
U
W
V
Answer:उत्तर:U
Positions: 6, 9, 12, 15, 18, ?.
Gaps: +3, +3, +3, +3, +3.
Missing letter = position 21 = U.
Example 2उदाहरण 2 · Letter series · Mediumमध्यम
Find the missing term: D, E, ?, J, N, S
I
G
H
F
Answer:उत्तर:G
Positions: 4, 5, ?, 10, 14, 19.
Gaps: +1, +2, +3, +4, +5.
Missing letter = position 7 = G.
Example 3उदाहरण 3 · Letter series · Hardकठिन
Find the next term: EU, HT, KS, NR, QQ, ?
PT
TQ
UP
TP
Answer:उत्तर:TP
First letters: E, H, K, N, Q → +3 each → T.
Second letters: U, T, S, R, Q → −1 each → P.
Next term = TP.
Example 4उदाहरण 4 · Letter series · Mediumमध्यम
Find the missing term: A, B, D, G, ?, P
M
K
J
L
Answer:उत्तर:K
Positions: 1, 2, 4, 7, ?, 16.
Gaps: +1, +2, +3, +4, +5.
Missing letter = position 11 = K.
Example 5उदाहरण 5 · Letter series · Mediumमध्यम
Find the missing term: G, H, J, M, ?, V
S
P
R
Q
Answer:उत्तर:Q
Positions: 7, 8, 10, 13, ?, 22.
Gaps: +1, +2, +3, +4, +5.
Missing letter = position 17 = Q.
Example 6उदाहरण 6 · Letter series · Mediumमध्यम
Find the missing term: K, L, ?, Q, U, Z
N
P
M
O
Answer:उत्तर:N
Positions: 11, 12, ?, 17, 21, 26.
Gaps: +1, +2, +3, +4, +5.
Missing letter = position 14 = N.
Common mistakesआम गलतियाँ
Forgetting to wrap from Z back to A.
Treating a two-letter group as one pattern.
Frequently asked questionsअक्सर पूछे जाने वाले प्रश्न
How do I solve letter series fast?
Convert letters to numbers and look at the differences.
What are common letter-series patterns?
Constant skips, increasing skips, alternating skips and mirror (opposite-letter) pairs.
Is number series the same?
It uses the same pattern-spotting idea; see Number Series under Aptitude.