Reasoning and General Intelligence – Series
A series is a sequence of numbers/alphabetical letters or both which follow a particular rule. Each element of series is called ‘term’. We have to analyse the pattern and find the missing term or next term to continue the pattern.
Reasoning & Ability – Series PDF Download
Types of series are explained in the following chart:
In number series, relationship between the terms is of any kind. For example.
- Consecutive even numbers
- Consecutive odd numbers
- Consecutive prime numbers
- Square of numbers
- Cubes of numbers
- Square root of numbers
- Omission of certain number of letter in any consecutive’ order
- Addition /subtraction/ multiplication/ division by some number (For Ex. A.P & G.P) or any other relation.
TYPES OF QUESTIONS:
- Complete the series
- Find Missing number of the series
- Find Wrong number of the series
EXAMPLES ON NUMBER SERIES
- Complete the series
EXAMPLE 1. Which of the following is the next term of series given below?
4, 6, 9, 13
(a) 17 (b) 18
(c) 19 (d) 20
Sol. (b) 4 6 9 13 Correct answer.
Reasoning Coding and Decoding Questions, Answers & Explanation PDF Download
EXAMPLE 2. Choose the next term of series given below. 64, 32, 16, 8, ?
(a) 0 (c) 2
(b) 1 (d) 4
Sol. (d) Each number is half of its previous number.
- To find the missing number of series:
EXAMPLE 3. What will come in place of question mark in the following series?
79, 87, ? , 89, 83
(a) 80 (b) 81
(c) 82 (d) 85
Sol. 81
EXAMPLE 4. What will come in place of question mark in the following series?
37, 41, ? , 47, 53
(a) 42 (c) 46
(b) 43 (d) 44
Sol. (b) Consecutive prime numbers.
EXAMPLE 5. What will come in place of question mark in the following series?
21, 34, ?, 89, 144
(a) 43 (c) 64
(b) 55 (d) 71
Sol. (b) Each number is the sum of the two preceding numbers.
21+34 = 55
34 + 55 = 89
55 + 89=144
(III) To find the wrong term in the series:
EXAMPLE 6. Find the wrong term in the series 3, 8, 15, 24, 34, 48, 63.
(a) 15 (c) 34
(b) 15 (d) 63
Sol. (c) 22 – 1, 32 – 1, 42– 1, 52– 1, 62 – 1
EXAMPLES ON ALPHABETIC SERIES
EXAMPLE7. What will come in place of question mark in the following series?
G, H, J, M, ?
(a) R (b) S
(c) Q (d) P
Sol. (c) Q
EXAMPLE 8. What will come in place of question mark in the following series? BF,CH,? HO,LT
(a) FG (b) EK
(c) CE (d) FJ
Sol. B) +2 +3 +4 +5
Reasoning Coding and Decoding Questions, Answers & Explanation PDF Download
EXAMPLES ON ALPHA-NUMERIC SERIES
EXAMPLE 9. What will come in place of question mark in the following series?
K 1, M 3, P 5, T 7, ?
(a) Y 9 (b) Y 11
(c) V 9 (d) V 11
Sol. (a) Alphabets follow the sequence
EXAMPLES ON MIXED SERIES
EXAMPLE 10. Complete the series
Z,L,X,J,V,H,T,F, __ ,__
(a) D,R (b) R,D
(c) D, D (d) R,R
Sol. (b) The given sequence consists of two series
(i) Z, X, V, T, __
(ii) L, J, H, F, __ Both consisting of alternate letters in the reverse order.
∴ Next term of (i) series = R, and
Next term of (ii) series = D
EXAMPLE 11. What will come in place of question mark in the following series?
7, 5, 26, 17, 63,37, 124, 65, ?, ?
(a) 101,215 (b) 101, 101
(c) 215, 101 (d) 215, 215
Sol. (c) The given series consists of two series
(i) 7,26,63,124….
(ii) 5,17,37,65…
In the first series,
7 = 23 – 1, 26 = 33 – 1, 63 = 43 – 1, 124 = 53 -1, ∴ 63 – 1 = 215
and in the second series.
5=22+ 1,17 = 42+l,
37 = 62 + 1,65 = 82 + 1,
∴ 102+1 = 101
EXAMPLES ON LETTER SERIES
EXAMPLE 12. Which sequence of letters when placed at the blanks one after another will complete the given letter series?
b a a b – a b a – b b a – –
(a) bbaa (b) aaaa
(c) abab (d) baba
Sol. (d) b a a b b a / b aab ba/ba.
