About this quiz
50 questions covering every section of the note on series method, add and multiply patterns, squares, cubes and primes, alternating series, letter series, letter shift, reverse and number coding.
This Lok Sewa practice set has 50 multiple-choice questions (Subject: Maths and IQ · For: Kharidar, Nayab Subba, Section Officer · Level: Medium). Take the quiz above first; after that, use the study list below to revise every question with its correct answer and a short explanation.
Study list: all 50 questions with answers and explanations
In a number series, the differences between neighbouring terms show no pattern. According to the step-by-step method, what should you try next?
- A) Guess the most common option
- B) Add all the terms together
- C) Find the ratios between neighbouring terms ✔
- D) Reverse the order of the series
Why: If the differences do not help, divide each term by the one before to look for a multiplying pattern.
Find the next term: 6, 13, 20, 27, ?
- A) 34 ✔
- B) 33
- C) 35
- D) 41
Why: The difference is always +7, so 27 + 7 = 34.
Find the next term: 81, 72, 63, 54, ?
- A) 46
- B) 44
- C) 36
- D) 45 ✔
Why: Each term is 9 less than the one before: 54 − 9 = 45.
Find the next term: 3, 4, 7, 12, 19, ?
- A) 26
- B) 28 ✔
- C) 27
- D) 31
Why: Differences are 1, 3, 5, 7 (odd numbers), so the next difference is 9: 19 + 9 = 28.
Find the next term: 5, 15, 45, 135, ?
- A) 270
- B) 225
- C) 405 ✔
- D) 145
Why: Each term is multiplied by 3: 135 × 3 = 405.
Find the next term: 2, 2, 4, 12, 48, ?
- A) 240 ✔
- B) 96
- C) 192
- D) 144
Why: The multipliers are × 1, × 2, × 3, × 4, so the next is × 5: 48 × 5 = 240.
Find the next term: 8, 27, 64, 125, ?
- A) 196
- B) 225
- C) 256
- D) 216 ✔
Why: These are cubes of 2, 3, 4, 5, so the next is 6 × 6 × 6 = 216.
Find the next term: 3, 8, 15, 24, 35, ?
- A) 46
- B) 48 ✔
- C) 49
- D) 50
Why: Each term is one less than a square (4 − 1, 9 − 1, 16 − 1, 25 − 1, 36 − 1), so the next is 49 − 1 = 48. Differences 5, 7, 9, 11, 13 agree.
Find the next term: 19, 23, 29, 31, 37, ?
- A) 41 ✔
- B) 39
- C) 43
- D) 45
Why: These are consecutive prime numbers; the prime after 37 is 41 (39 = 3 × 13 is not prime, and 43 comes after 41).
Which of the following is NOT a prime number?
- A) 41
- B) 43
- C) 47
- D) 51 ✔
Why: 51 = 3 × 17, so it has more than two factors. 41, 43 and 47 are primes.
Find the next term: 3, 20, 6, 30, 9, 40, ?
- A) 50
- B) 10
- C) 12 ✔
- D) 45
Why: Odd places go 3, 6, 9 (add 3) and even places go 20, 30, 40. The next term is in an odd place: 9 + 3 = 12.
Find the next term: 4, 12, 10, 30, 28, ?
- A) 26
- B) 84 ✔
- C) 56
- D) 90
Why: The operations alternate × 3 and − 2: 4 × 3 = 12, 12 − 2 = 10, 10 × 3 = 30, 30 − 2 = 28, so next is 28 × 3 = 84.
Find the next term: 3, 7, 15, 31, 63, ?
- A) 126
- B) 125
- C) 95
- D) 127 ✔
Why: Rule: × 2 then + 1. 63 × 2 + 1 = 127.
Find the wrong term in the series: 2, 6, 18, 54, 160, 486
- A) 160 ✔
- B) 18
- C) 54
- D) 486
Why: Each term should be × 3: 54 × 3 = 162, not 160. Then 162 × 3 = 486 fits.
What is the position of the letter R in the English alphabet?
- A) 17
- B) 19
- C) 18 ✔
- D) 9
Why: Counting from A = 1 (or from O = 15 using EJOTY), R is the 18th letter. Its reverse position is 9.
Find the next term: C, F, I, L, ?
- A) N
- B) O ✔
- C) P
- D) M
Why: Positions are 3, 6, 9, 12 (add 3), so the next is 15, which is O.
Find the next term: Y, V, S, P, ?
- A) M ✔
- B) N
- C) L
- D) O
Why: Positions are 25, 22, 19, 16 (subtract 3), so the next is 13, which is M.
Which letter is the opposite partner of H (A pairs with Z, B with Y, and so on)?
- A) R
- B) T
- C) Q
- D) S ✔
Why: H is at position 8; its partner is at 27 − 8 = 19, which is S.
If LION is coded as MJPO, how is TIGER coded?
- A) SHFDQ
- B) UJHER
- C) UJHFS ✔
- D) UIHFS
Why: Each letter moves +1 (L to M, I to J, O to P, N to O). So T, I, G, E, R become U, J, H, F, S.
If WATER is coded as YCVGT, how is FIRE coded?
- A) GJSF
- B) HKTG ✔
- C) HKSG
- D) DGPC
Why: Each letter moves +2 (W to Y, A to C, T to V, E to G, R to T). So F, I, R, E become H, K, T, G.
In a code each letter is replaced by its opposite letter (A by Z, B by Y and so on). How is FACE written?
- A) UZXW
- B) VZXU
- C) GBDF
- D) UZXV ✔
Why: Use 27 minus the position: F 6 to U 21, A 1 to Z 26, C 3 to X 24, E 5 to V 22. So FACE becomes UZXV.
If MANGO is written as OGNAM, how is APPLE written?
- A) ELPPA ✔
- B) EPLPA
- C) APPLE
- D) ELPAP
Why: The letters are simply written in reverse order: A, P, P, L, E becomes E, L, P, P, A.
If BAG is coded as 10 because 2 + 1 + 7 = 10, what is the code for HEN?
- A) 25
- B) 26
- C) 27 ✔
- D) 28
Why: H = 8, E = 5, N = 14, and 8 + 5 + 14 = 27.
If "red" is called "blue", "blue" is called "green" and "green" is called "yellow", what is the colour of a clear sky called?
- A) Blue
- B) Green ✔
- C) Yellow
- D) Red
Why: A clear sky is really blue, and in this code "blue" is called "green", so the answer is green.
If SEND is coded as TGQH, how is CODE coded?
- A) DPEF
- B) DQFI
- C) EQGI
- D) DQGI ✔
Why: The shift grows with position: +1, +2, +3, +4 (S to T, E to G, N to Q, D to H). So C+1 = D, O+2 = Q, D+3 = G, E+4 = I, giving DQGI.
Find the next term: 2, 5, 10, 17, 26, ?
- A) 37 ✔
- B) 35
- C) 36
- D) 39
Why: n²+1: 6²+1 = 37.
Find the next term: 1, 4, 9, 16, 25, ?
- A) 36 ✔
- B) 30
- C) 49
- D) 35
Why: Squares.
Find the next term: 1, 8, 27, 64, ?
- A) 125 ✔
- B) 100
- C) 81
- D) 216
Why: Cubes: 5³.
Find the next term: 2, 6, 12, 20, 30, ?
- A) 42 ✔
- B) 40
- C) 36
- D) 44
Why: n(n+1): 6×7.
Find the next term: 1, 1, 2, 3, 5, 8, ?
- A) 13 ✔
- B) 11
- C) 12
- D) 15
Why: Fibonacci.
Find the next term: 7, 14, 28, 56, ?
- A) 112 ✔
- B) 84
- C) 70
- D) 100
Why: ×2.
Find the next term: 100, 50, 25, 12.5, ?
- A) 6.25 ✔
- B) 6
- C) 5
- D) 10
Why: ÷2.
Find the next term: 4, 9, 19, 39, 79, ?
- A) 159 ✔
- B) 149
- C) 158
- D) 160
Why: ×2+1.
Find the next term: 2, 3, 5, 7, 11, 13, ?
- A) 17 ✔
- B) 15
- C) 19
- D) 16
Why: Primes.
Find the next term: 120, 99, 80, 63, 48, ?
- A) 35 ✔
- B) 36
- C) 34
- D) 32
Why: n²−1: 6²−1.
Find the missing term: 3, 9, ?, 81, 243
- A) 27 ✔
- B) 18
- C) 36
- D) 54
Why: ×3.
Find the next term: 1, 2, 6, 24, 120, ?
- A) 720 ✔
- B) 600
- C) 240
- D) 840
Why: Factorials.
Find the next term: A, C, E, G, ?
- A) I ✔
- B) H
- C) J
- D) K
Why: Skip one letter.
Find the next term: Z, X, V, T, ?
- A) R ✔
- B) S
- C) Q
- D) P
Why: −2.
Find the next term: AB, DE, GH, JK, ?
- A) MN ✔
- B) LM
- C) NO
- D) KL
Why: Skip one letter between pairs.
Find the next term: B2, D4, F6, H8, ?
- A) J10 ✔
- B) I9
- C) K11
- D) J9
Why: Even letters with position.
If CAT is coded as DBU, then DOG is coded as:
- A) EPH ✔
- B) EOH
- C) DPH
- D) FPH
Why: Each letter +1.
If APPLE is coded as ELPPA, then MANGO is coded as:
- A) OGNAM ✔
- B) ONGAM
- C) MAGNO
- D) NAMGO
Why: Reversed.
If 1 = A, 2 = B..., then 8-5-12-12-15 is:
- A) HELLO ✔
- B) HELPS
- C) HILLO
- D) HALLO
Why: Positions.
If DOG = 26 (4+15+7), then CAT =
- A) 24 ✔
- B) 26
- C) 22
- D) 27
Why: 3+1+20.
If PEN is coded as QFO, then INK is coded as:
- A) JOL ✔
- B) HMJ
- C) JOK
- D) KOL
Why: +1.
If BOOK is coded as YLLP (opposite letters), then COLD is coded as:
- A) XLOW ✔
- B) XLWO
- C) YLOW
- D) XKOW
Why: C↔X, O↔L, L↔O, D↔W.
In a code, ROAD is written as URDG. How is SWAN written?
- A) VZDQ ✔
- B) VXDQ
- C) UZDQ
- D) VZCQ
Why: +3 to each letter.
Find the wrong term: 3, 9, 27, 81, 242, 729
- A) 242 ✔
- B) 81
- C) 27
- D) 729
Why: Should be 243.
Find the next term: 1, 3, 6, 10, 15, ?
- A) 21 ✔
- B) 20
- C) 18
- D) 25
Why: Triangular numbers (+6).